Witnesses of a violent assault that took place in Whanganui on Thursday evening say a man with a knife was seen at the scene.
A New Zealand Police spokesperson said an assault took place in the Duncan St and Moana St area about 5pm.
One person was taken to Wellington Hospital and is in a critical condition.
One witness told the Chronicle a man with a knife was seen outside a building near the scene of the attack.
The witness said the man was knocking on the windows of the building, appearing to threaten people inside Pizza Kingdom.
The three people locked the door to the store and called for support, the witness said.
They were later joined outside by another group of people who together got into an altercation with the man.
Whanganui field crime manager Inspector Paul Baskett said police were appealing for information in relation to the assault.
Baskett asked for anyone who had electronic recordings, CCTV or eyewitness accounts of the incident to speak with them.
Baskett also asked for people who lived near the scene of the attack to look around their property for any discarded objects and to report any suspicious objects to police immediately.
"It is important that if you know who is responsible for this attack that you come forward and tell police what you know."
No one has been arrested in relation to the assault and the investigation is ongoing.
Police said anyone with information can contact police on 105 and quote file number 220512/6199.
Alternatively, information can be given to Crime Stoppers anonymously on 0800 555 111.