Aucklanders are waiting anxiously for the clock to strike noon and the city is sent back into alert level 3.
Police roadblocks will be set up at entrances to the Auckland region and the Government is working on a legal notice to make masks mandatory for Aucklanders out and about in public.
After 102 days without community transmission, four members of the same Auckland family tested positive for Covid-19 and the origin of infection is unknown.
Prime Minister Jacinda Ardern made the announcement at a hastily arranged press conference last night that Auckland would be returning to level 3 today at noon for at least three days.
"We are asking people in Auckland to stay home to prevent the spread," Ardern said.
"We have done it before and we can all do it again."
It's been 85 days since the country was last in alert level 3.
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.
The rest of New Zealand is in alert level 2 and people must maintain physical distancing of 2m, wear a mask if physical distancing isn't possible like on public transport. Gatherings are limited to 100 people.
Ardern urged Aucklanders not to rush to the supermarket to stock up on food and goods, but her message was ignored, as many supermarkets experienced an overwhelming demand.
Countdown supermarkets moved to immediately restrict the sale of some staple products to ensure demand could be met. General manager corporate affairs Kiri Hannifin told Newstalk ZB's Mike Hosking that the move was designed to prevent stockpiling.
The family with the four new cases live in south Auckland and the workplaces of two members of the household have close, with some workers also showing symptoms, Health Minister Chris Hipkins said.
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.
The economic impact of another lockdown will be huge, economists have warned.
An estimated 28 per cent of Auckland's workforce cannot operate under level three - that's about 250,000 jobs - Infometrics reported.
A senior economist at Infometrics said the restrictions announced on Tuesday evening alone could knock around 0.2 per cent off New Zealand's economic output in the September quarter and less spending and productivity in Auckland will hit the rest of the country.
Based on the spending patterns seen across New Zealand last time the country was under alert level 3 "you're looking at around $60-$69 million less being spent over the next three days alone [in Auckland] under the level three lockdown", Brad Olsen said.
The new cases of unknown infection has 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," Collins said this morning.
"Basically it is very little time."