Auckland has been put back into lockdown after New Zealand recorded its first cases of COVID-19 following 102 days without any domestic transmission in the country.
Prime Minister Jacinda Ardern on Tuesday announced four confirmed cases of the virus in one Auckland family, adding that the source was unknown.
The index case was a person in their 50s from South Auckland, the Ministry of Health said in a press release.
The person had been symptomatic for five days but had not reported any overseas travel prior to their positive test result.
Household contacts of the original case received a rapid test and three of these tests also came back positive, while three were negative, the ministry said.
Anyone who came into contact with the person will be traced and tested for COVID-19, as is the usual protocol, it added.
All close contacts of the four cases will remain in self-isolation for 14 days, regardless of their test result, and all casual contacts will remain in self-isolation until they have the results of their tests.
Arden said that Auckland, New Zealand's largest city, would be moved to Alert Level 3 from midday on Wednesday through midnight on Friday with bars and many other businesses closed. Citizens will be asked to stay at home.
Traveling into Auckland will be forbidden unless people are residents returning home.
The rest of the country will be raised to Level 2 until Friday, which will see gatherings limited to 100 people and attendees required to socially distance from each other.
"These three days will give us time to assess the situation, gather information, make sure we have widespread contact tracing so we can find out more about how this case arose and make decisions about how to respond to it once we have further information," Ardern said at a news conference late on Tuesday.
"I know that this information will be very difficult to receive," she added. "We had all hoped not to find ourselves in this position again. But we had also prepared for it. And as a team, we have also been here before."
Social media users posted pictures of the large queues that formed outside grocery shops after the local measures were announced.
New Zealand was praised internationally for its response to the coronavirus pandemic after the virus' spread was stopped by the introduction of a strict lockdown in late March when only 100 people had tested positive.
The World Health Organization had applauded the country prior to Tuesday saying it was an example to others for having "successfully eliminated community transmission".
New Zealand had not recorded community transmission since May 1.