Auckland will spend a full fortnight in lockdown after New Zealand's fresh COVID-19 cluster grew to at least 30 people on Friday.
Health officials announced another 12 confirmed and one probable case, including two in the Waikato town of Tokoroa, 200km from Auckland.
That led Prime Minister Jacinda Ardern to extend the city's "level three" lockdown through to Wednesday, August 26, two weeks after it began.
Around 1.5 million Aucklanders are being asked to stay home, except for essential work, supermarket shopping, exercise or health reasons.
The rest of New Zealand will remain at "level two", with police-run checkpoints between Auckland and other regions to stop all non-essential travel.
"Our overall COVID-19 strategy remains elimination," Ms Ardern said.
"That requires the ongoing stamping out of the virus any time that it comes back.
"Together we have got rid of COVID before. We have kept it out for 102 days. Longer than any other country.
"We have a world leading COVID response with the result that many lives were saved and our economy was getting going faster than almost anywhere else again.
"We can do all of that again."
The first community outbreak in more than three months has thrown New Zealanders back into the clutches of the pandemic, after weeks of restriction-free living.
The country's health officials swung into "rapid response" mode after the discovery of the community cases.
A new record was set on Thursday when more than 15,000 Kiwis were tested for COVID-19; a dramatic ramp-up of previous efforts.
However, there has been heavy criticism of the government for not testing workers within the country's border and quarantine regime.
A Newshub investigation revealed around two-thirds of workers had not been tested prior to the new cluster, breaking government pledges.
Epidemiologist Sir David Skegg said he was "really shocked" by that "extraordinary" failure.
"(Testing them) every two or three weeks frankly would be quite inadequate," he told Radio NZ.
"But it now turns out that nothing like that was being achieved."
Health Minister Chris Hipkins admitted testing of affected workers was too low.
"I would have liked to see more tests earlier, yes it would be fair to say," he said.
Director General of Health Ashley Bloomfield said he hoped case numbers would continue to stabilise rather than grow.
"There is some heroic work out there ... this is exactly the sort of pace we had geared up for," he said.
"I'm never pleased to see another case but I'm pleased we are identifying additional cases."
The government will also extend its wage subsidy to support business through the new outbreak.
By and large, Kiwis are responding as best as can be to the new outbreak.
More than one million New Zealanders and more than 20 per cent of Kiwis have downloaded the official contact tracing app.
However, Dr Bloomfield also said he'd received reports of abuse or attacks towards some health workers, labelling that "completely unacceptable".
Ms Ardern has also announced she will take the weekend to decide whether to hold firm to the country's election date, September 19, or push it back.
Air New Zealand has also slashed flights in and out of Auckland.