At least 97 Palestinians and 13 soldiers were killed as Israel ramped up a major military offensive in the bloodiest single day in Gaza in five years.
As regional leaders met in Doha for urgent talks on a ceasefire, the Gaza Palestinian death toll soared to 435, with a spokesman for the emergency services saying more than a third of the victims were women and children.
The Israeli army said 13 soldiers had been killed in a series of attacks inside Gaza on the third day of a major ground operation.
"Over the course of the day, 13 soldiers from the IDF's Golani Brigade were killed in combat in the Gaza Strip," an army statement said.
Their deaths raised to 18 the total number of soldiers killed since Israel's ground operation began late on Thursday. It was the largest number of soldiers killed in combat since the 2006 Lebanon war.
Most of Sunday's Palestinian victims were killed in a blistering hours-long Israeli assault on Shejaiya near Gaza City, which began before dawn and has so far claimed 62 Palestinian lives, with another 250 wounded.
With ambulances unable to reach the area, the International Committee of the Red Cross called for an urgent temporary ceasefire to allow paramedics to evacuate the dead and wounded, which was agreed on by the two sides.
Inside the ravaged neighbourhood, there were hellish scenes of carnage and chaos as a convoy of ambulances moved in to make the most of the calm, an AFP correspondent said.
Entire buildings were collapsed on themselves or strewn into the streets, while others were still ablaze, sending pillars of black smoke skywards.
There were also bodies, blackened and charred almost beyond recognition, some with whole limbs missing.
As the violence raged, Palestinian president Mahmud Abbas arrived in Qatar to discuss a ceasefire with Hamas leader Khaled Meshaal, with UN chief Ban Ki-moon due there later Sunday at the start of a regional tour to push truce efforts.
So far, truce efforts have been rejected by Hamas.
Undaunted by the Israeli bombardment by land, sea and air, it has pressed on with its own assaults.
Following a night of terror in Shejaiya, thousands began fleeing for their lives at first light after heavy shelling left casualties lying in the streets, an AFP correspondent reported.
Clouds of black smoke billowed into the sky as the shelling continued and Gaza's eastern flank burned.
Among those fleeing was a group of gunmen with automatic weapons, some with their faces covered by scarves.
Women and children were among the dead, as were a Palestinian paramedic and a cameraman killed when the ambulance they were in was hit.
"He wasn't a fighter, he was a fighter for humanity," wailed one relative as the family buried him. "He was an ambulance worker, did he deserve to die?"
So far, UNRWA has opened 61 of its schools to shelter those fleeing the most heavily bombarded areas, with more than 81,000 people taking refuge in them, the UN's Palestinian refugee agency said.
Israeli Prime Minister Benjamin Netanyahu has put the blame for civilian casualties squarely on Hamas, accusing it of "using innocent civilians as human shields".
An end in sight?
Speaking 24 hours after the ground operation began, Israel's Chief-of-Staff Lieutenant General Benny Gantz warned there would be "moments of hardship", alluding to the possibility of further Israeli casualties.
Although Israel said earlier today it was expanding its ground operation to destroy the network of tunnels used by militants to stage cross-border attacks, Netanyahu also said troops could end their mission "fairly quickly".
But he demanded international action to demilitarise the tiny coastal enclave, which is home to 1.7 million Palestinians and is one of the most densely populated areas on the planet.
"I think the international community has to... undertake a programme to demilitarise Gaza and to change the situation because it's unacceptable," he told CNN's "State of the Union" talk show.
US Secretary of State John Kerry blamed Hamas for perpetuating the conflict, urging it to "be responsible and accept... a multilateral ceasefire without conditions".
But Turkey's Prime Minister Recep Tayyip Erdogan accused Israel of killing Palestinians "mercilessly" and lashed out at Washington for turning a blind eye to Gaza's suffering.
"How can we ignore this? How can a country like the United States turn a blind eye to this?" he asked.
"As a member of the UN Security Council, it needs to act fairly."
Meanwhile, at Gaza City's Shifa hospital, casualties were being brought in by the minute during the morning, among them many children peppered with shrapnel wounds and screaming in agony.
"This is the worst I've ever seen it," said Dr Said Hassan, who has worked at the hospital for eight years.