Two Auckland workplaces have been shut down and Rotorua is on high alert, following close contact with people infected with Covid-19.
There are four confirmed cases from an unknown source in the country's largest city.
As a result, Auckland is now at Covid-19 Alert Level 3, and the rest of New Zealand at Level 2.
The restrictions will last until at least midnight on Friday, while the health response ramps up.
The Director General of Health, Dr Ashley Bloomfield, says a woman in her 20s, who's tested positive, travelled to Rotorua with a family of four at the weekend while she was symptomatic.