NZ Police shot and killed the man on Friday at Countdown supermarket at New Lynn, a southwest suburb of Auckland.

St John say three patients are in a critical condition at Auckland City Hospital.

A further three patients – one in a serious condition and two in moderate conditions – have also been taken to hospitals across Auckland.

Ardern said the attack was carried out by a Sri Lankan national who arrived in 2011 and was on a terror watchlist from 2016.

“A violent extremist undertook a terrorist attack,” Ms Ardern said.

“It was senseless and I’m so sorry that happened.”

Police Commissioner Andy Coster said the man was under constant surveillance, and was trailed by undercover officials as he visited the supermarket.

Coster said the man picked up the knife used in the attack in the store, and was shot and killed within 60 seconds of the attack taking place.

Ardern said she was unable to share many details around the man’s circumstance because of court-issued suppression orders.

“I can tell you that agencies were using every single possible means available to them to protect the New Zealand public from this individual. Every single possible means,” she said.

Frightening first-hand reports have emerged in the hours since the attack.

Newshub reports Amit Nand was at the supermarket during the attack.

“People were running up to me saying ‘go outside because people are being stabbed’ … I saw him with a knife,” he said.

“I went past him, I went by him with another guy and I told him to ‘drop the f***ing knife.”

Nand says he was then approached by an undercover cop.

“The cop is like ‘get back’ and he started shooting him five times and killed him.”

Michelle Miller, a resident of nearby Avondale, told Radio NZ she saw a man “running around with a knife, then he just lost the plot”.

“It’s horrific. I feel sorry for the Countdown staff, I feel sorry for the people who were actually hurt here today,” she said.

“The police have done an amazing job. They had the guy try to give himself up but he wouldn’t. It’s really sad that they had to do what they had to do.”

Countdown spokeswoman Kiri Hannifin said staff were “devastated” by the attack.

“Our hearts are heavy knowing what our team and customers have witnessed and been through,” she said in a statement.

New Zealand is currently in a national lockdown to fight a COVID-19 outbreak, with Auckland at strict level four settings.

The attack is New Zealand’s second supermarket stabbing this year, after an unrelated incident at a Countdown store in Dunedin which left four people injured.