One of them is a 20-year-old woman who flew from San Francisco to Auckland on March 21 on flight NZ7 and then Auckland to Christchurch on March 21 on flight NZ527.
Another woman in her 20s who flew from London via Dubai and Sydney to Christchurch on March 13 on flight EK006 also tested positive for Covid-19.
The infection of a man in his 50s is linked to an already confirmed case in Canterbury, said the Ministry of Health.
Meanwhile, another man in his 50s tested positive after flying from Sydney to Christchurch on March 13 on flight EK412.
Details around the new case of a 50 year-old woman who has also tested positive are yet to be released. A female teen from Canterbury is also listed as a probable COVID-19 case.
Yesterday, there were three new confirmed cases of Covid-19 in the Canterbury region. Two of the cases confirmed on Tuesday were a man and a woman in Christchurch, both in their 60s, who are relatives of a confirmed case.
The other is a man in his 20s in South Canterbury who flew into NZ from Switzerland on March 16 via Abu Dhabi on flight EY0052.
A state of emergency has now been declared in New Zealand after the number of new confirmed and probable cases of Covid-19 across the country increased by 50, including five in a school.
Director-General of Health Dr Ashley Bloomfield said there were 47 confirmed cases and three probable cases bringing the total number of confirmed and probable cases to 205.
There were now five community cases related to Auckland's Marist College.
The cases connected with the school and the cases connected with the World Hereford Conference in Queenstown, were both being treated as "clusters", Dr Bloomfield said.
Staff and students from that college should not have contact with other people, Bloomfield said, and they should also keep their distance from people in their own households.
"We do have some community transmission in New Zealand."
Four were confirmed and number of other cases were being treated a potentially community transmission.
Six people are in hospital in a stable condition, one in Rotorua, two in Waikato and three in Wellington. None of those patients are in intensive care. Three patients treated for Covid-19 were discharged yesterday, one each from Lakes District Hospital in Queenstown, Waikato and Thames hospitals.
There were 1400 tests processed yesterday, bringing the total number of tests so far to 9780.
Dr Bloomfield said there would continue to be a rise in the number of cases for 10 days, and they would only "turn around" if people followed lockdown rules.
"That turn around will happen if all New Zealanders do what is being asked of them."
State of emergency declared today
Sarah Stuart-Black, director of Civil Defence Emergency Management, said a state of national emergency would be declared in Parliament today.
At 12.21pm, the state was declared by the Minister for Civil Defence Peeni Henare.
This provided access to special powers to combat Covid-19 - including powers of requisition and closing roads, and stopping people from doing certain activities.
Stuart-Black said these powers sat alongside other powers to ensure essential services could stay up and running.
"Each of you has a role in helping to save a life," she said.
A mobile alert will be sent between 6pm and 7pm tonight to advise New Zealanders about the state of emergency.
Stuart-Black would be empowered by the state of emergency powers, but she said it would be great if she didn't have to use them.
The legislation allowed the state of emergency to remain in place for seven days, but this can be extended.
"We're really hoping people have heard the messages and understand how horrendous this could get."
Stuart-Black said there would also be no tolerance for people who do not self-isolate.
"We have emergency services available now, the police would have the powers necessary."
Police would give a statement about the escalation that will occur, but the message in the first instances was helping people understand the importance of staying home unless they had a reason to be out in public.
Stuart-Black said a number of issues still needed to be worked through when asked about people in emergency shelters, and homeless people.
Agencies could be used to enforce self-isolation - and if police needed additional support from the military, that was possible.
"I'm hoping it's not going to be necessary."
She said the move to alert level 4 was significant and people needed to take heed of that advice.
"This will be adding a huge amount of anxiety ... you've still got a TV and access to the water from the tap."
Emergency powers could be used but most New Zealanders will stay at home, and in recent emergencies including fires and earthquakes and the mosque shootings, Kiwis had done the right thing to keep themselves safe, Stuart-Black said.
Bloomfield said people should act responsibly. If people went hunting and needed to be rescued, they would take health workers away from the Covid-19 frontlines.
Ministry of Business, Innovation and Employment deputy chief executive Paul Stocks said employers should pass the Government's wage subsidy scheme on to workers - and if there were cases where that was not happening, MBIE and the Ministry of Social Development would like to know.
The Council of Trade Unions has expressed concern about cases where employers were not passing on the wage subsidy, or forcing workers to take sick leave during the lockdown.
Stocks said that should not be happening.
Lockdown begins tonight
New Zealand will move to alert level 4 at midnight tonight and will be in nationwide lockdown for at least four weeks - a move Prime Minister Jacinda Ardern says is necessary to prevent up to tens of thousands of unnecessary deaths.
The taskforce's press conference, scheduled for 1pm, includes:
• Sarah Stuart-Black, Director of Civil Defence Emergency Management – update on Covid-19 national response
• Dr Ashley Bloomfield, Director-General of Health – health update
• Peter Elms, Immigration NZ national manager – border issues update
• Paul Stocks, Deputy Chief Executive MBIE – essential services update
Yesterday the number of confirmed and probable cases rose to 155, including 12 who had recovered and six who were in hospital but have not needed ICU treatment.
Of the 155 total there had been 15 Covid-19 cases in the South, including two new confirmed Dunedin cases yesterday and one probable Dunedin case.
