As Auckland returned to lockdown, New Zealand's "rapid response" contact tracing swung into gear in a mad dash to contain the country's first COVID-19 outbreak in three months.
Eight cases of the deadly virus have been identified in the last 24 hours - four confirmed and four probable - linked to one south Auckland family.
Two members of that family visited Rotorua on the weekend, though health authorities maintain the focus of their efforts is on Auckland.
New Zealand's biggest city returned to a 'level three' lockdown at noon on Wednesday, shutting many businesses, schools and largely keeping 1.5 million Aucklanders at home.
The lockdown is a sharp departure from the life Aucklanders were living for the last three months, but Prime Minister Jacinda Ardern justified the decision by pointing to the resurgence of the virus in Australia.
"There were 322 new cases of COVID-19 in Australia yesterday. 664 people are in hospitals, 54 in intensive care units and 39 on ventilators," she said.
"Our response to the virus so far has worked.
"We know how to beat this. But we also know we don't need to look far to see what it can mean if we don't get on top of it.
"We have a plan. And now's the time to follow it."
That plan has seen all 208 close contacts of the family - including every employee of two linked businesses - contacted and isolated in an effort to contain the virus.
Genomic testing will be carried out to try to ascertain how the family caught COVID-19, which from April until this week had been contained to the country's mandatory isolation border regime.
The rest of NZ has moved to 'level two' restrictions, which requires social distancing and caps the size of gatherings.
Aged care homes have moved to the strict 'level four' in a precautionary move; most of New Zealand's 22 deaths from COVID-19 have taken place at rest homes.
As part of the response, Aucklanders are being asked to wear a mask for the first time through the pandemic - though Ms Ardern is yet to make it mandatory.
"Think of it as a duty to one another. It's a proven line of defence ... it's also a sign you care about your community and our team of five million," she said.
Five million masks will be handed out, and Air NZ has asked passengers leaving Auckland to wear masks on their flights.
Police have set up checkpoints around Auckland to allow only essential traffic to move in an out of the region.
The NZX 50 Index was shocked by the news, dropping 2.5 per cent in early trading before finishing 1.3 per cent lower.
Auckland's level three lockdown will initially last for 60 hours, from midday on Wednesday to midnight on Friday.
Ms Ardern said Cabinet would use all the information gathered by Friday to make a decision on whether to extend, end, deepen or lessen the restrictions.
That meeting will also consider the country's election date, currently set for September 19, but now under a cloud.
The opposition has called for the poll, due by November, to be deferred to later this year or even 2021.
Australian Associated Press