Five people have been stabbed at a Countdown supermarket in Dunedin, on Cumberland St at about 2:30pm today, according to the Otago Daily Times.
Three of those stabbed are in a critical condition, while the other two are suffering moderate injuries, a St John spokesman said.
Emergency services were called to the scene and four people were taken by ambulance to Dunedin Hospital.
One person was taken into an ambulance with what looked like a neck wound. Another was stretchered into an ambulance, the newspaper reports.
A third who was in Countdown uniform came out with a bandaged shoulder. Another who also appeared to be a staff member was taken out of the supermarket with shoulder and head injuries.
One person, who was seen covered in blood, was taken into custody by police just minutes after the incident.
Prime Minister responds
In her weekly post-cabinet meeting press conference, Prime Minister Jacinda Ardern discussed the attack in Dunedin.
She says there was nothing that suggests it was a domestic terror event, from the Police's perspective.
"Police will, however, release new information as it comes to hand," she says.
"Needless to say, such an attack is concerning to acknowledge the real early reports of courageous acts of bystanders who have taken action ito protect those around them."
"Our thoughts are with all those affected by this attack."
Jacinda said Dunedin Police would hold a press conference at 5pm to provide more information.