Prime Minister Jacinda Ardern and Director of General Health, Dr Ashley Bloomfield announced four news cases at a surprise media briefing at 9.25pm Tuesday.
An Auckland family of four tested positive for the virus on August 10.
With no link to overseas travel or any isolation facilities, Ardern placed the city into Alert Level 3.
"I know this information will be very difficult to receive," Ardern said.
Since the announcement, there have been 13 further cases of Covid-19 in the community.
However, what does this mean for Christchurch, a city with no active community cases?
The Prime Minister announced the rest of the country would move into Level 2 at midday August 12.
This level and its restrictions are set to last for three days.
Cantabrians should now reinforce social distancing rules to prevent any potential spread of the virus.
This means keeping a two-metre distance between yourself and others.
Dr Bloomfield suggests that in situations where these rules cannot be maintained, the public should wear face masks.
"This is a tricky virus," Bloomfield said.
Ardern also placed a ban on mass gatherings over 100 people.
Weddings, birthdays, funerals and tangihanga are included in the list of gatherings.
Unlike Auckland, Christchurch schools remain open, however health officials advise students and teachers to enforce strict hygiene practices, and socially distance where possible.
The Ministry of Education website suggests children and staff who are at higher-risk of severe illness should take additional precautions when leaving home.
Hospitability businesses must keep groups of customers separated, however other businesses must only follow physical distancing and record-keeping guidelines.
Jacinda Ardern asked New Zealanders, no matter where they live, to look after each other and to check on neighbours.
"We will get through this."
More information about New Zealand's 4-level Alert System can be found online.