* The level 3 and 2 rules - all you need to know and what you can and can't do
* Motorways, supermarkets busy as Aucklanders prepare for new lockdown
* Schools in Auckland advised to close immediately
* 'NZ's worst nightmare' - how world media reacted to country's return to lockdown
* Virus expert: Covid may already be circulating across Auckland
* What the new levels mean for sport
* Pupil from infected family attended Auckland primary school
Auckland is back in level 3 lockdown, with region-wide police checkpoints planned and a stronger presence at supermarkets.
Super City residents were scrambling earlier today to prepare for the midday restrictions, with lengthy queues forming outside supermarkets and Covid-19 testing centres.
Police road blocks will be set up at entrances to the Auckland region.
The Government indicated this morning that it could seek a legal notice requiring mandatory mask use for anyone out in public in Auckland.
However Prime Minister Jacinda Ardern later clarified that masks would not be mandatory. Instead she "strongly encouraged" everyone to wear a mask, scarf or bandana to cover their face.
The possibility of making masks mandatory would be considered at a later date.
Supermarkets plan to ration essential items to avoid stockpiling and Air NZ will require all travellers flying from Auckland to wear masks.
Economists are warning that at least another three days of lockdown will be devastating for businesses: an estimated 28 per cent of Auckland's workforce cannot operate under level three - that's about 250,000 jobs.
Earlier: Auckland scrambles to prepare for lockdown
New Zealand's biggest city will move back into alert level-3 lockdown from midday today, and the rest of New Zealand into level 2.
Countdown supermarkets are moving to immediately restrict the sale of some staple products to ensure demand can be met. General manager corporate affairs Kiri Hannifin told Newstalk ZB's Mike Hosking that the move was designed to prevent stockpiling.
Air New Zealand will close its Auckland lounges and valet parking service at midday today.
"Customers on flights departing from Auckland will be also be required to wear masks," the airline said today.
"Customers are welcome to bring their own, or these will be provided by the airline onboard. Air New Zealand recommends that its customers traveling from other ports also wear masks, however this will not be a requirement."
Air NZ's front of house staff and domestic cabin crew will be wearing masks and gloves.
"Customers who hold a ticket for a domestic flight within New Zealand and are scheduled to depart before 11.59 PM Sunday 16 August may opt to hold their fare in credit and can do this via the airline's online booking tool."
A Civil Defence alert was sent to mobile phones at 6.55am today, following a similar alert last night. "If you are in Auckland, STAY HOME where possible and follow Alert Level 3 guidelines. This will stop the transmission of Covid-19 and SAVE LIVES," the alert said.
Four cases from same family: PM
Prime Minister Jacinda Ardern announced the return to levels 3 and 2 last night after confirming four cases of community transmission in South Auckland - all from the same family, but with no known source.
TVNZ is reporting the man in his 50s who has tested positive works the night shift at a business and three of his colleagues are waiting for their test results.
His wife works in a central Auckland suburb and was tested at a West Auckland GP which is now closed. Their daughter goes to a primary school in Mt Albert.
Health Minister Chris Hipkins confirmed work colleagues of one of the family members are also showing symptoms. There are reports at least two colleagues are affected so far.
He said it was a "relatively small" workforce affected.
One of the children in the family attends Mt Albert Primary School - the school is closed for 72 hours and the child has been tested, according to a health notice. Officials are awaiting the test results.
"Auckland Regional Public Health Service and the Ministry of Education will work with the school principal to decide if there has been any exposure to Covid-19 at the school. A decision will be made about whether there needs to be testing at the school," the health notice says.
Hipkins told Newstalk ZB's Mike Hosking the family had been offered quarantine but he did not know if they had been moved yet. "The family is being very cooperative; I imagine they will take up the offer."
"The first I heard of this was between 3pm and 3.30pm yesterday," Hipkins said. "The director general [of health] was the first person who notified me."
The restrictions will last for three days - at this stage - and end at midnight on Friday.
Hipkins said the Government would be testing about 50,000 people by the end of the week. "We will know a lot more in 72 hours than we do now."
Auckland Mayor Phil Goff has told RNZ people should expect police roadblocks on motorways in and out of the city.
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Impact on Auckland businesses
Brad Olsen, senior economist at Infometrics said that the restrictions placed on Auckland would have an impact on the wider economy.
"By our estimate, around about 28 per cent of Auckland's workforce cannot operate under level three, that's about 250,000 jobs. We're likely to see that number of people not operating," Olsen said.
Based on the spending patterns seen across New Zealand last time the country was under alert level three "you're looking at around $60-$69 million less being spent over the next three days alone [in Auckland] under the level three lockdown."
The restrictions announced on Tuesday evening alone could knock around 0.2 per cent off New Zealand's economic output in the September quarter, Infometrics estimated.
"The question is at the moment, both for Auckland and the rest of the country, do we see any shift to level four in the near term, do we see basically the extension of level three for an extended period, or even level two.
"But at the moment what I think it points to is this is going to hit businesses just as everyone thought things were getting better … The big highlight is, it's not over and it won't be over for a long, long time."
A slowing of activity in Auckland would hit activity elsewhere.
"Not that we have different regions operating under different levels, you've got to remember just how important Auckland is, just from an economic point of view.
"Not only is it a good third to 40 per cent of the nation's economy, but at the same time there are such critical linkages there that you could well see a slight slowing in activity across the rest of the country just because Auckland's not operating at its normal capacity."
Compared to the first lockdown, there was a question of "the economic ramifications of whether or not people abide by the lockdown in the sense that if they don't and they have to extend it for a longer period, that of course that causes longer and further economic damage".
Retail NZ says the move back into lockdown is a blow for the industry that was yet to get back on its feet after more than eight weeks under lockdown earlier this year.
"My heart really sank when I heard the news - it's really disappointing for everyone in New Zealand, but especially for those businesses that have been struggling to recover from the lockdown that ran from March to May," Greg Harford, chief executive of Retail NZ, told the Herald.
"It could well be the nail in the coffin for a number of small businesses that just don't have the resources to survive another period."
Meanwhile Auckland Chamber of Commerce chief executive Michael Barnett told Newstalk ZB's Mike Hosking today that his "heart sank" when he heard about a fresh lockdown from today.
He said the moves would be "destructive and confusing" for business-owners and he was hoping to see a full, detailed response from the Government.
"If it goes beyond three days, it's going to be devastating for the economy."
New cases cast doubt over next month's election
National leader Judith Collins told MediaWorks it was too soon to say if the September 19 election should be delayed. The issue could be considered depending on what happened on Friday, when the latest alert levels are reviewed.
"It's going to be very difficult to have an election in mid-September when we are now mid-August. Basically it is very little time," she said this morning.
Collins said New Zealanders did not want to see a postal ballot system, which was "so easily" ignored by voters.
Collins told RNZ she would like the dissolution of Parliament, which is due to happen this morning, to be delayed.
There would be "no opportunity at all" to debate issues if needed.
National will delay its campaign launch. "It seems difficult for us to have it."
"I can't see how we can have the Government can say 'It's all just fine and we'll get the Electoral Commission to do postal votes'," she said.
"I think it's going to have to be [delayed] unless it's sorted out by Friday."
Aucklanders asked to stay home
Ardern told media at a hastily arranged press conference last night: "We are asking people in Auckland to stay home to prevent the spread.
"We have done it before and we can all do it again."
It comes after four cases of community transmission from the same family were confirmed yesterday - the first such cases in 102 days. The source of infection is unknown.
Level 3 means public facilities, businesses, restaurants and cafes will shut — as will schools unless they have students whose parents are essential workers — and most people will be required to work from home.
The area covered by level 3 is the Super City — from Wellsford in the north to Pukekohe in the south.
"Act as if you have Covid, and as though people around you have Covid," Ardern said.
Pharmacies and supermarkets will remain open, and Ardern said there was no reason to panic-buy.
"Please do not rush to the supermarket tonight ... there is no reason to rush out and make any purchases this evening."
Aucklanders should use a mask if they leave the house to access essential services. The rest of the country should wear a mask in situations where they can't socially distance.
Ardern said Aucklanders should keep an eye out for their neighbours. "We have come too far to go backwards. Be strong and be kind. We know what to do because we have successfully done this before."
For the rest of New Zealand, mass gatherings will be limited to 100 people.
Director general of health Ashley Bloomfield also advised aged residential care facilities to stop all visits, given how vulnerable older people were to Covid-19.
He said the four confirmed cases were in one family acquired from an unknown source, with no link to overseas travel or managed isolation.
Ardern said more than one workplace was involved, and it wasn't just one distinct suburb in Auckland that was likely affected. Officials were now contact tracing and trying to establish the source of infection.
An Auckland man in his 50s was tested on Monday after showing symptoms. He had no history of overseas travel and was tested a second time yesterday. Both tests were positive.
There were six other people in his family, three of whom had also tested positive, including a preschool child. The other three tested negative. Close contacts have been isolated for 14 days regardless of test results. Casual contacts are also being isolated.
Bloomfield said he expected to find other cases because officials didn't know the infection source.
He declined to give the ages of the confirmed cases, but said the man had a fever and cough, and his partner also had strong symptoms.
He wouldn't specify what suburb they lived in, and the workplaces were "beyond South Auckland".
Ardern said without confirming the source, a precautionary approach was needed, "as disruptive as it is".
Despite calls for calm, news of the return to lockdown sparked frantic scenes at supermarkets last night as shoppers scrambled to stock up.
Countdown's online shopping website crashed under demand.
Auckland Mayor Phil Goff called for calm and patience.
"I am urging Aucklanders to come together like we did last time to stamp out community transmission. Please remain calm, please do not panic-buy and please follow the lockdown rules."
The Principals' Federation advised last night that all Auckland schools should close immediately rather than waiting until midday.
Federation president Perry Rush said schools were still waiting to hear from the Ministry of Education but most schools were already contacting parents to ask them to keep children at home.
Meanwhile, the lockdown will disrupt the election campaign.
Ardern said she would remain in Wellington. The National Party and New Zealand First both said their parties would suspend their campaigns immediately.Staff reporters
What you need to know
Moving into alert level 3 at midday today for three days.
Under Alert Level 3, you are encouraged work from home if you can.
Travel and self-isolation:
If you are in Auckland and do not live in Auckland, the Ministry of Health suggests you go home. Practise good hygiene and be conscious of your health. It is recommend bubbles are kept small.
Businesses are able to open, but should not physically interact with customers. Essential services including healthcare, justice services and businesses providing necessities are able to open. Bars and restaurants should close, but takeaways are allowed.
Schools in Auckland will have limited capacity. Where possible it is encouraged students learn from home.
When you're out and about:
Maintain physical distancing of 2 metres outside your home, including on public transport. It is highly recommended that you wear a mask if you are out and about.
Public transport can continue to operate with strict health and safety requirements. You should maintain physical distancing and wearing a mask.
Public venues should close. This includes libraries, museums, cinemas, food courts, gyms, pools, playgrounds and markets.
Gatherings of up to 10 people can continue, but only for wedding services, funerals and tangihanga. Physical distancing and public health measures should be maintained.
People at high risk of severe illness such as older people and those with existing medical conditions are encouraged to stay at home where possible, and take additional precautions when leaving home.
Rest of the country
Moving into alert level 2 at midday today for three days.
You can still continue to go to work and school, with physical distancing.
Wear masks if you can in public.
No more than 100 people at gatherings, including weddings, birthdays, funerals and tangihanga.
Businesses can open to the public if they are following public health guidance, which include physical distancing and record keeping.
People at higher risk of severe illness from Covid-19, for example those with underlying medical conditions and old people are encouraged to take additional precautions when leaving home.
Practice good hygiene - stay home if sick.