Mayor Phil Goff has urged Aucklanders to remain calm as the city heads into a three-day level 3 lockdown.
From midday on Wednesday Auckland will be in level 3 lockdown, while the rest of New Zealand will go into level 2 lockdown.
Prime Minister Jacinda Ardern made the announcement on Tuesday night after four people were diagnosed with COVID-19. It is unknown how the people, who are from the same family, became infected.
Dr Ashely Bloomfield said close contacts including work colleagues were being tested.
Goff tweeted after the news broke calling for Aucklanders to come together to stamp out community transmission.
"I understand that people are probably feeling a little bit scared, a little angry and a little confused right now. None of us wanted to go back into a lockdown, but we always knew this was a very real possibility."
Goff told people to follow the Ministry of Health guidelines and observe good hygiene.
He also told people to stay calm and not panic buy, something Ardern had also stated earlier.
New Zealand had not recorded any cases of community transmission for over 100 days.
