At least four people have been injured at a supermarket-stabbing in central Dunedin on South Island in the afternoon.

Authorities said three people have been critically injured and are being treated in hospital.

New Zealand Prime Minister  Jacinda Ardern said the motivation behind the attack is not yet clear. 

Police said that the suspect to the incident has been taken into custody.

Police are responding to an incident in central Dunedin.

It occurred on Cumberland St at about 2.30pm.

Initial information suggests several people have been injured.

One person has been taken into custody.

Further information will be released when available.