Prime Minister Jacinda Ardern is warning cafes and bars that they can be forcibly shut and is urging New Zealanders to stay home immediately - even though the nationwide lockdown doesn't come into force until 11.59 tonight.
The lockdown looms as the number of global cases hits 400,000 and more than 17,000 deaths. Hopes that the Italian death toll was slowing have been dashed after the second highest number of deaths in a day - 743.
The World Health Organisation (WHO) has warned the United States could overtake Europe as the next epicentre of the global coronavirus pandemic.
More than 46,400 cases of Covid-19 have now been confirmed across the US and 591 people have died, but a WHO spokeswoman said she was expecting those numbers to surge.
"We are now seeing a very large acceleration in the number of cases from the US, so it does have that potential [to overtake Europe]," Dr Margaret Harris said. "We cannot say that that is the case yet, but it does have that potential. They have a very large outbreak and an outbreak increasing in intensity."
In New Zealand, Ardern has moved to ease the fallout by revealing a 48-hour reprieve for those unable to make it home by tonight, extending visas for tens of thousands of migrant workers and international students, and negotiating a six-month holiday for mortgage repayments.
Bunnings, Mitre 10 and Placemakers will be open for essential building and construction, but not for the general public.
The Warehouse will close, as will liquor stores unless they are within a Licensing Trust Area and have a "one-in, one-out" rule.
Food delivery services will only be permitted for Meals on Wheels or for non-pre-cooked food; Uber Eats and Deliver Easy will not be allowed to operate.
Yesterday shops and cafes remained open, including in downtown Wellington, where people paid little attention to the 2m physical distancing rule.
Shoppers also continued to ignore pleas against panic-buying as a fight broke out at a Napier Pak'N Save over a chicken, liquor sales spiked 1800 per cent, and even pet stores were inundated as people prepared for lockdown.
Told of cafes and retails shops that were open yesterday, Ardern demanded to know names and added: "The medical officer of health should be making a visit."
Under the Health Act, the officer can close premises for public health reasons.
"No bars, no restaurants. We should be in shutdown now for those services," Ardern told media yesterday.
"Obviously it takes time for us to get to a position where everything is settled into alert level 4, but I want people to apply that as if it's already arrived."
It was necessary to save thousands of lives, she said.
Cabinet is understood to have been shown multiple medical models that ranged in the number of estimated deaths - from 40,000 to 100,000 - for different scenarios of widespread community transmission.
There were 40 new cases in New Zealand yesterday, bringing the total number of confirmed or probable cases to 155, including 12 who had recovered and six who were in hospital but have not needed ICU treatment.
The number of new cases was again the biggest daily increase since March 16.
Community transmission cases have doubled from two to four, including one in Orewa, two in Auckland, and one in the Wairarapa.
Yesterday the World Health Organisation described the pandemic as "accelerating", as the number of cases worldwide neared 400,000.
New Zealanders are set to join about 1.7 billion people worldwide - more than a fifth of the world's population - who will stay at home.
Those in the UK joined the latest on lockdown notice. Prime Minister Boris Johnson ordered the measures after the number of deaths in the UK reached 335. The toll rose further overnight, to 422.
Similar lockdowns have been imposed in other parts of Europe including Germany, Italy, Spain and France, as well as across Canada, Australia and the US - though US President Donald Trump insisted the US would soon be open for business.
Parliaments around the world have also been adjourned, and New Zealand's Parliament will pass a motion today to adjourn until April 28.
Yesterday the Government moved to ease the anxiety of tens of thousands of temporary visa holders in New Zealand.
All temporary work, student and tourist visas due to expire between April 1 and July 9 will be extended until late September. Those whose visas were expiring before April 1 can apply for a new visa.
"We are trying to be as flexible as we can be," Ardern said, adding that many of those workers would be vital as they worked in the aged-care sector.
Finance Minister Grant Robertson announced $6.25b to underwrite bank loans for small to medium businesses, as well as a six-month mortgage-repayment holiday for homeowners whose income was hit by coronavirus.
But there was so far nothing for renters beyond a rent freeze and potential income protection through the wage subsidy scheme, which also applies to homeowners.
Many Kiwis continued to bombard media with questions about how alert level 4 will work, and Ardern conceded the need to move to lockdown swiftly had left the Government's task force flying somewhat blind.
And further clarity on essential services would be provided today, including the home delivery of non-food products.
Meanwhile Kiwis overseas were told to settle where they were as the number of flights home continued to dry up.
Ardern said getting home now would be "very difficult", and overseas travellers in New Zealand who faced a similar dilemma should also prepare for the four-week lockdown.
She added that Kiwis offshore coming home would face more stringent quarantine, but she was still working out where they could be placed without turning a place of quarantine into a petri dish.
She stressed the need for people to limit contact with others.
"Every interaction we have with someone else increases the risk of spreading the virus. Stay at home. That is the simplest way to save lives."
People in lockdown should stick to their "bubbles" which, for most people, are those in their households.
Couples who don't live together or parents with shared custody could be in the same bubble, as could the "buddy" of a person living alone - but bubbles shouldn't overlap.
"You can't spend time with other people outside of your bubble."