Four people have been injured, three critically and one seriously, during a stabbing spree at a central Dunedin supermarket.

Shoppers watched in horror as the attack occurred on Monday at the central Dunedin Countdown. Armed police are on the scene and one person has been taken into custody.

The attack took place at a Countdown supermarket in the city on the South Island at around 2.30pm New Zealand time (12.30pm AEST).

RNZ reported a witness saying the offender was carrying two knives.

One witness at the supermarket told Stuff: “It just sounded like someone fell over and then screaming got louder and louder.

“We walked past the aisle and we heard someone say, ‘he has got a knife’, so we just kept moving forward.”

Asked what the person looked like, the man said: “Curly hair, quite a messy little fellow.”

It is understood a woman received stab wounds to her hands, while another person had to be revived inside the supermarket.

Prime Minister Jacinda Ardern told media there was nothing at this stage that suggested it was a domestic terror event.