New Zealand hikers trekking down from Mount Everest base camp have described their panic when the devastating quake hit.
Nepal's Home Ministry says the death toll from yesterday's devastating earthquake has reached 1805.
The latest toll puts the overall regional fatalities at 1865 and at least 4700 people have been injured in the magnitude 7.8 earthquake.
An avalanche triggered by the quake yesterday swept across Nepal's Mount Everest region, killing at least 18 climbers and guides, and slamming into a section of the mountaineering base camp.
Numerous climbers may now be cut off on routes leading to the top of the world's highest peak.
Lachlan Davis, of Wellington, was in the Himalayas on his way down from Mount Everest when everything began to "roar", he said.
He had been at base camp just two days before.
"The quake shook the mountains an incredible amount and it came with a massive long roar which was multiple land slides and avalanches at once.
"[It] was definitely the most intense quake I've felt and I live in Wellington."
Mr Davis said his group passed numerous people on the trail to Everest because it was peak trekking and climbing season.
They were now in Namche and were trying to get back to Kathmandu to get their bags and get on the first plane out, he said.
"The path ahead of us was damaged by landslides so we were lucky where we were," Mr Davis said.
"Given the state of the trail at certain points I think it likely some tourist climbers and trekkers would have died or been injured."
New Zealander Guy Cotter of Adventure Consultants was leading a party of seven Kiwis on Mt Everest.
Adventure Consultants operations manager Caroline Blaikie confirmed the group was safe at Camp One but said others in the area needed help.
Ms Blaikie said the company contacted the group via satellite phone.
"There's limited communication with the Nepalese cellphone networks as well."
Landlines were available in lower valleys.
"Right now at Everest Base Camp the key need is for helicopters to be evacuating casualties from there. That's underway at the moment."
She said other camps in the area were devastated and people needed clothes and other e
Ms Blaikie understood Mr Cotter witnessed several avalanches after the quake, and it must have been a terrifying experience
This afternoon it was confirmed that two Nepali staff of Adventure Consultants have died as a result of the avalanche.
The New Zealand-based Mt Everest guiding company said the Everest Base Camp avalanche appeared to have been caused by a large chunk of ice being dislodged by the earthquake.
Steve Moffat, the Wanaka-based company's New Zealand operations manager, said from Wanaka he understood the avalanche consisted of a "massive blast" of powder snow triggered ice falling off Pumori and Lingtren, mountains that rise above the base camp in the Khumbu Glacier.
International media reports vary, some saying 10 and one that at least 17 people have died at the base camp.
Adventure Consultants has now lost five staff at Everest in two seasons. Three of its local staff were killed in the Everest avalanche which killed 16 Nepalese last April.
In addition to its base camp contingent, the company has 10 climbers and four guides, including expedition leader Guy Cotter, at Camp 1 at 5900m just above the Khumbu icefall.
Mr Moffat said all those at Camp 1 were safe and well. It was still early in the Everest climbing season and no teams had gone above Camp 1 yet.
"I know there's a lot of supplies at Camp 1 and Camp 2 so the people up there, there's numerous teams up there right now, they are safe where they are and they have food and fuel to survive."
"I imagine areas of the Khumbu icefall will have been affected by the ground shaking causing damage to the route they take. As far as I know no one is attempting to drop from Camp 1 at this stage."
"It's fine weather this morning Nepal time," Mr Moffat said at 3.30pm today. "I believe a rescue helicopter had made it into base camp and I would imagine picking up injured people."
'Eerily quiet' on city streets
Prue Smith - general manager of the Himalayan Trust New Zealand - is in Katmandu.
She has just come back from the mountains where she has been visiting a lot of villages before the earthquake.
At 6.30 am Nepal time, she said there had been continuing aftershocks and she was awake most of the night.
"It's early morning here, but it's eerily quiet. Most people have slept outside but there is little traffic on the road, as you would normally see.
"We are waiting to check in with the people in our communities up in the mountains to find out the level of damage.
"The trust has 67 schools that we directly support so I'm fully expecting that there will be some damage. I expect we will be launching an appeal.
"But I have no internet access and communications are a real problem."
Kerikeri woman Lucy Dunn said she was on the fourth floor of her hotel in Pokhara when the "absolutely massive" quake hit.
She hiked down from base camp on Thursday and said it was lucky she had got to the village of Pokhara where there was no real visible damage.
Friends she had hiked with were in Kathmandu sleeping in a tent because the roof of their hotel had collapsed in the quake, she said.
"We hid in a door frame after realising we were maybe too high up to get down. When it slowed we grabbed our stuff and ran down. Everyone was out on the streets.
"We didn't go back into our hotel until night time and have slept in the lobby by the door all night. [We've] not slept a wink actually but lay here for a quick escape in case."
Kiwis safe and well
Earlier today, the Ministry of Foreign Affairs and Trade (Mfat) confirmed the well-being of just over 100 New Zealanders in Nepal.
A statement from Mfat said the New Zealand High Commission and Honorary Consul in Nepal continued to seek information about the welfare and whereabouts of any New Zealanders in the affected area.
Communication networks in the affected area, including in Kathmandu, have been disrupted following the earthquake, making it difficult to contact New Zealanders, Mfat said.
The Nepalese Government has declared a state of emergency in affected areas and appealed for international assistance after the severe quake destroyed homes, businesses and temples in Kathmandu and the densely-populated surrounding areas.
Officials confirmed that more than 1400 people have died as rescue teams continue to search for survivors who are feared to be trapped under rubble. The death toll is expected to rise.
Yesterday's quake collapsed houses, toppled centuries-old temples and cut open roads in the worst tremor in the Himalayan nation in more than 80 years.
New Zealand mountaineer Russell Brice runs one of the best-known Everest guiding operations Himalayan Experience. He and two guides from New Zealand were preparing climbers for an Everest summit, when the avalanche struck base camp.
Among the Himalayan Experience team were several climbers attempting to summit Everest again after last year's deadly avalanche hampered attempts.
Mr Brice has emailed family and friends of climbers at base camp through his organisation to say they, and their Sherpa staff, were all safe.
Mr Brice said the large communal tent from the Himalayan Experience camp was being used as a make-shift medical centre for the dozens of injured people at base camp.
At least seven New Zealanders in a party led by Guy Cotter of Adventure Consultants are also on the mountain.
Last night, Adventure Consultants operations manager Caroline Blaikie confirmed the group was safe at Camp One.
"We believe there has been some major damage in Everest base camp.
"We don't have confirmation of the situation regarding casualties or what exactly has happened in base camp however, we do know our base camp manager and other base camp staff we have there from New Zealand and the US are safe."
Helicopter assistance was not immediately available to base camp because of adverse weather conditions. The bad weather was forecast to last through to Thursday.
Kiwi experiences in Nepal
Prue Smith, the general manager of the Himalayan Trust NZ, was holed up in a car park after the quake struck 81km northwest of Kathmandu on Saturday.
"It was absolutely awful. It was an ongoing rolling and rumbling and shaking," she told NZ Newswire.
"I'm not from Christchurch but I now completely understand - it was the most unpleasant experience."
Smith was sitting in the garden of a hotel with friends in Thamel, a part of Kathmandu popular with tourists, when the earthquake struck.
"Rubble came down from the buildings and from the walls around us," she said.
Smith said some buildings had collapsed and people were being dug out of the rubble.
Kiwi journos in Nepal
Three Kiwi journalists spoke of diving under a table as plaster and other items fell around them. Fairfax journalists Mike Scott and Matt Rilkoff, and Waikato Times chief photographer Peter Drury were in a restaurant near Kathmandu's largest Buddhist temple when the quake struck.
Scott described the terrifying moments. "It went on for about a minute and it was f ***** g scary," he told stuff.co.nz
The trio saw a blood-soaked monk being carried out of the building, thousands of people standing in the road and collapsed buildings.
New Zealand-Nepal Connection
New Zealand has a close relationship with Nepal.
The Himalayan Trust NZ was founded by Sir Edmund Hillary, who conquered Mt Everest in 1953 with Nepali Tenzing Norgay.
More than 4000 climbers have scaled the 8,850-meter (29,035-foot) summit since 1953. The numbers have skyrocketed in recent years, with more than 800 climbers during the 2013 spring season.
Following the 2014 avalanche, guides accused Nepal's government of not doing enough for them despite making millions in permit fees from Western mountaineers who attempt to scale the Himalayan peaks. The guides protested by refusing to work on the mountain, leading to the cancellation of last year's climbing season.
TV crew finished shooting days before quake
The New Zealand film crew behind TV One's upcoming drama Hillary had left Nepal three days before the earthquake.
The crew of 15 people, including The Hobbit star Dean O'Gorman, concluded extensive shooting in Kathmandu a few days before the quake, and had captured many shots of the city, including monuments and buildings, before the devastation.
The crew had travelled to India, where producer Carmen Leonard said everyone "was shaken but ok" after experiencing the massive earthquake in Varanasi, 350 kilometres from Kathmandu.
Executive producer, Philip Smith, said the crew had an incredible two weeks in Nepal, falling in love with the country, and being embraced by the people. "It's a terrible way to end such a wonderful experience," he said.
Australians in Nepal
More than a dozen Australians are reported missing. Since the earthquake hit, families have been putting the names of missing loved ones on The Red Cross's Family Links website.
On Sunday morning, there were more than a dozen Australians on the list.
Among them is Perth woman Ballantyne Paige Forder, who is believed to have been working in an orphanage in Kathmandu at the time of the quake.
Her Tasmanian-based sister Amanda-Sue Markham says the family has yet to hear from the 20-year-old.
"We're trying not to get too worried but of course the pictures that are emerging out of Nepal - we're trying not to look at them," Ms Markham told the Nine Network.
Ms Forder is due to return to Australia on Wednesday, her sister said.
"It's her 21st birthday on the third of May. She was coming home for her 21st birthday so we really would like to celebrate with her. We just need to get her home."
Australian actor Hugh Sheridan is also pleading for information about his 20-year-old brother Zachary."Please. Anyone who is awake, please pray for my little brother Zachary who is on Mt Everest," he tweeted. "I'd appreciate every prayer you have spare."
Other people from Melbourne, Brisbane, South Australia and Tasmania are also on the Red Cross list.
The Department of Foreign Affairs and Trade is yet to release a statement about any Australians who might have been caught up in the disaster.
The federal opposition has called on the Abbott government to offer every assistance towards the recovery effort in Nepal.
"Labor has asked the government for urgent advice about the safety of Australians reported to have been in the area at the time," Opposition foreign spokeswoman Tanya Plibersek said in a statement on Sunday.
There were also fears for a teenage adventurer trying to become the youngest Australian to climb Mount Everest, however she is reportedly safe.
A message posted to Alyssa Azar's Facebook page said the 18-year-old was on the mountain at the time, but had returned to base camp.
'Alyssa has contacted us and let us know that she was out climbing when this happened but is back at Base Camp now safe and sound,' the post reads. 'She is feeling good and waiting to see what results come from this.'
Nepal earthquake and aftershocks
The quake with a preliminary magnitude of 7.8 struck before noon and was most severely felt in the capital as well as the densely populated Kathmandu Valley. A magnitude-6.6 aftershock hit about an hour later, and smaller aftershocks continued to ripple through the region for hours.
The earthquake also shook several cities across northern India, and was felt as far away as Lahore in Pakistan, Lhasa in Tibet, and in Dhaka, Bangladesh.
The quake's epicentre was 80km northwest of Kathmandu, and it had a depth of only 11km, which is considered shallow in geological terms. The shallower the quake the more destructive power it carries.
The Kathmandu Valley is densely populated with nearly 2.5 million people, and the quality of buildings is often poor.
The US Geological Survey revised the magnitude from 7.5 to 7.9 then lowered it to 7.8. It said the quake hit at 11.56 am local time at Lamjung. It was the largest shallow quake since the 8.2 off the coast of Chile on April 1, last year.
An earthquake's power increases by 10 times with each increase in the number of its scale. A magnitude 7 quake is capable of widespread and heavy damage while an 8 magnitude quake can cause tremendous damage.
This means yesterday's earthquake was 22 times more powerful than the 7.0 quake that devastated Haiti in 2010.
Nepal suffered its worst recorded earthquake in 1934, which measured 8.0 and all but destroyed the cities of Kathmandu, Bhaktapur and Patan.
Google relaunches 'Person Finder' in aftermath of disaster
The tool is a searchable, online database to help people track down their loved ones who are involved in the disaster.
The 7.8 magnitude earthquake, which killed almost 1400 people and destroyed homes, also damaged communications in the region.
Person Finder collates information from emergency responders and individuals who post details about relatives missing or found.
Within hours of the disaster, 200 names had been uploaded.
The tool was first launched in response to the 2010 earthquake in Haiti, and has been used in several major disasters ever since including the 2011 Japanese tsunami and 2013 Boston Marathon bombing.
NGOs offering aid
World leaders and global charities offered condolences and emergency aid to Nepal following the earthquake while grappling to understand the scope of the disaster.
With Internet and cellphone communications spotty, and many roads closed due to damage, the outside world did not yet have a clear picture of what is most needed following the earthquake that authorities say has killed more than 1,000 people.
But it was clear that help was needed - and fast.
Oxfam's director in Nepal, Cecilia Keizer, said the level of damage was still emerging.
"People are gathered in their thousands in open spaces, it's cold and dark and they are scared to go into their houses as there have been over 50 aftershocks. Some areas are in absolute ruin.
"Communication is very challenging. Telephone lines are down and electricity has been cut off making charging mobile phones difficult. Water is also cut off."
Oxfam India Humanitarian Response Manager, Zubin Zaman, said the earthquake was "grim news" for the people of Nepal.
"The first step in an emergency like this is getting clean water to people who need it most, helping to prevent the spread of water-borne diseases and other health risks which turn one terrible disaster into another," he said.
Mr Zaman was on stand-by to go to Nepal. "We've been working all day and all night to make sure we to get the full picture of the situation and coordinate with other aid agencies to make sure all the urgent needs of those worst affected are met.
"We'll know more in the coming hours, but given the level of poverty in-country already, this is grim news for the people of Nepal."
Do you know anyone in Nepal? Contact us here
Oxfam Australia chief executive Helen Szoke says a group of disaster specialists from the UK is flying in with supplies.
"People are gathered in their thousands in open spaces and are scared, as there were several aftershocks," Dr Szoke said in a statement.
"Oxfam staff in Nepal, along with thousands of others, are sleeping outside tonight in football fields and other open spaces because they are the safest place to be."
"We are treating it as a big emergency," said Ben Pickering, Save the Children's humanitarian adviser in Britain. "We know the damage is extensive and that access into rural areas will be very, very difficult for everybody."
"Children will be affected in many ways. Physical injuries. Separated from families," he said. "The priority now is understanding the scale, what the emergency needs are right now and in the coming weeks."
Several charities were assembling disaster teams - based on the assumption that sanitation, shelter and medical help are urgently required - but the most convenient pathway into Nepal was not available because the international airport in Kathmandu was shut down by the quake.
Pickering said Save the Children plans to send a specialist team as soon as possible to help with food, water and sanitation.
Doctors Without Borders said four teams would leave Sunday morning for Nepal from Bihar state in India, where the charity has worked since 2007 and which is close to the Nepal border. The organization is also sending in 3,000 kits including medical supplies.
AmeriCares has also sent a team from India and is preparing shipments of medical aid and relief supplies. "We are prepared to help any way that we can," said AmeriCares President and CEO Michael J. Nyenhuis. "This is a terrible tragedy and our hearts go out to the families suffering."
Mica Bevington, spokeswoman for Handicap International, which was already established in Nepal with 47 workers, said, "One of our projects there, because it's earthquake-prone, is to help hospital staffs, physical therapists and others to anticipate the kind of injury we tend to see after a quake. ... Many of the people we were helping were already disabled, so today we're helping get them to safety. And we're sharing our resources, like all our wheelchairs are going to two hospitals in need."
French aid group Doctors of the World (Medecins du monde) said it has mobilized its workers in Nepal - based in Kathmandu and Chautara to work on maternal and infant health - to help quake victims. It is sending more staffers and medical aid to the region immediately.
Unicef New Zealand's Executive Director Vivien Maidaborn said the aid organisation feared for the safety of children affected by the disaster.
"New Zealand and Nepal have a long established bond and we know many Kiwis will be wanting to help Nepal in whatever way they can. Every dollar donated will make an enormous difference to children who need urgent help.
"We need to keep our promise to Nepal's children to always be there for them - in this emergency and every day."
Unicef has prepositioned supplies, including water purification tablets, hygiene kits, tarpaulins and nutrition supplies, and is working with government and other partners to meet children's immediate needs in the areas of water and sanitation, child protection, health and nutrition.
The International Federation of Red Cross and Red Crescent Societies (IFRC) is preparing to mount an international emergency response to the earthquake.
Volunteers and staff of Nepal Red Cross Society are working on the ground assisting in search and rescue efforts and administering first aid to the injured.
The Red Cross blood bank in Kathmandu is also providing blood supplies to the main medical facilities in the capital.
The Red Cross has limited stocks of emergency relief items available in the country and ready to be distributed. The IFRC is also activating its logistics systems in Kuala Lumpur and Dubai in readiness to mobilise additional relief materials.
"We are extremely concerned about the fate of communities in towns and villages in rural areas closer to the epicentre," said Jagan Chapagain, IFRC Director for Asia Pacific.
"Roads have been damaged or blocked by landslides and communication lines are down preventing us from reaching local Red Cross branches to get accurate information. We anticipate that there will be considerable destruction and loss of life."
The IFRC is mobilising resources from its hubs in New Delhi, Kuala Lumpur and Bangkok and is releasing funds from its Disaster Response Emergency Fund to support the initial emergency response.
Countries offering aid
Foreign Minister Murray McCully said New Zealand was ready with financial and practical assistance for Nepal.
"New Zealand is considering options and is keen to provide help as soon as the Nepali authorities indicate what would be most useful in the context of the wider international response," Mr McCully said.
"Although it will take some days to learn the full extent of the tragedy, the casualty toll in dead and injured and the damage to Nepal's infrastructure and economy are clearly massive."
Mr McCully said efforts were continuing to account for all New Zealanders in Nepal at the time of the earthquake.
"New Zealand expresses its deepest condolences to the people of Nepal. We know from recent experience the suffering an earthquake of this magnitude can bring," he said.
Nepalese authorities allowed Indian Air Force planes to bring in 43 tons of relief material, including tents and foods, and nearly 200 rescuers from India's National Disaster Response Force, India's External Affairs Ministry spokesman Vikas Swarup said.
The planes were returning to New Delhi with Indian nationals who were stranded in Kathmandu. India's state-run Air India announced that it would begin relief flights to the Nepalese capital today.
China dispatched a 62-member search and rescue team for Nepal, the official news agency Xinhua reported. The group, including six sniffer dogs and carrying rescue and medical equipment, was set to reach the capital Kathmandu by midday to "carry out humanitarian rescue", the report said.
The European Union is considering "some budget support" to Nepal, according to a joint statement Saturday by the EU's foreign policy chief, development chief and humanitarian chief. It did not provide details or amounts.
They said the EU is also looking into "how we can help Nepal to deal with the destroyed and damaged buildings and how to help its citizens."
"The full extent of the casualties and damage is still unknown but reports indicate they will likely be high, both in terms of loss of life, injuries and damage to cultural heritage," they said.
British Prime Minister David Cameron, German Chancellor Angela Merkel and other leaders also promised help for Nepal. Cameron said on Twitter that Britain "will do all we can to help those caught up in it."
Norwegian Foreign Minister Boerge Brende said the Scandinavian country would allocate 30 million kroner ($3.8 million) to aid work, and that the money would be sent through the United Nations and charitable organizations.
"We are following the situation closely and we will find out whether to contribute further when we know more," Brende said in a statement.
Italy's Foreign Ministry said it has made available 300,000 euros ($326,000) of emergency aid for earthquake victims. The aid will be channeled through the International Red Cross.
French President Francois Hollande said France is "ready to respond to requests for help and assistance" from Nepalese authorities. The tiny, wealthy country of Monaco said it would send emergency aid "in the coming hours."
The US Embassy in Nepal announced $1 million in initial aid and the U.S. Agency for International Development activated an urban search and rescue team.
Among other countries sending condolences was Mexico, which suffered an 8.1-magnitude earthquake that killed an estimated 9,500 people in the nation's capital in 1985. Mexico's foreign ministry said it stood in solidarity with the government of Nepal and the relatives of the earthquake victims.
In New York, Uma Mysorekar, president of the Hindu Temple Society of North America, said the disaster requires "global assistance."
"We fear the deaths and casualty numbers could go up for days," she said. "We from the temple society will be collecting funds and forwarding them - as soon when we know where to send them."-
-NZME., AAP, AP, AFP and Mail Online contributed to this report.