A KNIFE-WIELDING attacker has stabbed four people in a New Zealand supermarket, critically injuring three, in a rampage authorities said was “random” and not terror related.

Police said the attack – highly unusual in the normally peaceful South Pacific nation – occurred at a Countdown supermarket in the city of Dunedin at 2.30pm (3.30am Irish time) on Monday. A man has been taken into custody.

Witnesses told local media a man carrying two knives stabbed staff in the supermarket and bystanders who tried to stop him were also injured.

The most recent mass-casualty attack in New Zealand was the Christchurch mosques shootings in March 2019, when a white supremacist gunman murdered 51 Muslim worshippers and severely injured another 40.

Prime Minister Jacinda Ardern said her first question to police was whether the Dunedin attack had national security implications but they assured her it did not.

“At this stage, there’s nothing to suggest from the police’s perspective that this is what they would define as a domestic terror event,” she told reporters.

Southern police district commander Paul Basham characterised the incident as a “random attack” and said the perpetrator would face court on Tuesday.

Authorities initially reported five people were stabbed but later revised it down to four, with Basham saying the attacker received a minor injury during the incident.

He described the actions of those who stopped the man as “nothing short of heroic”, saying they had prevented more injuries.

Basham said three of the victims were due to undergo surgery overnight.

Countdown’s managing director Spencer Sonn said everyone at the supermarket chain was “shocked and devastated” by the attack.

New Zealand introduced tough gun laws in the wake of the Christchurch attack to limit access to firearms.