New Zealand Prime Minister Jacinda Ardern said four new cases of coronavirus were confirmed late Tuesday, ending the country's streak of 102 days without community transmission.

In an urgent press conference, Ardern said the four cases were from one household in Auckland. However, the source of the infection is not known.

File photo shows News Zealand Prime Minister Jacinda Ardern.(Getty/Kyodo)

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As a precaution, Auckland will be placed under Alert Level 3 coronavirus restrictions for three days beginning midday on Wednesday. The restrictions include requiring people work and study from home, and limiting public gatherings to 10 people.

The rest of the country will move to Alert Level 2.

"These three days will give us time to assess the situation, gather information, make sure we have wide-spread contact tracing," Ardern said.

For the first time, New Zealanders are being encouraged to wear masks when unable to socially distance, such as when on public transport.

"As a team, we have also been here before. We know if we have a plan and stick to it...we can work through it," Ardern said.

"We have come too far to go backwards."