A 37-year-old Danish citizen is suspected of killing five people in a bow-and-arrow attack in the Norwegian town of Kongsberg in a rare incident of mass killing in Norway, police say.

Two people, including an off-duty police officer, were wounded in the Wednesday night (local time) attacks, which happened in different locations in the town, 68 kilometres south-west of the capital, Oslo.

“The police are giving this information because of all the rumours on social media regarding people who are not linked to these very serious acts,” police said in a statement in which they gave the suspect’s nationality but did not identity the person.

The suspect, who was apprehended, was believed to have been acting alone, police said.

They said nothing about a possible motive.

The death toll was the worst of any attack in Norway since 2011, when far-right extremist Anders Behring Breivik killed 77 people, most of them teenagers at a youth camp.

The attacks went on for more than half an hour over a “large area” of Kongsberg, including at a Coop Extra grocery store, the Aftenposten newspaper cited police as saying.

A woman living near the shop said she had heard alarms as she was walking home.

“I saw a group of police officers, including one who held several arrows in his hand,” Marit Hoefle told the newspaper.

Investigators are considering whether the attacks amounted to an act of terrorism, and said they would give a more detailed account of the incident later on Thursday.

Police were interrogating the suspect and he was co-operating, his lawyer said.

“He is co-operating and is giving detailed statements regarding this event,” Fredrik Neumann told public broadcaster NRK.

A bow and arrow were used in at least some of the attacks, police said, adding they were investigating whether there was also another weapon.

Images from one of the crime scenes showed an arrow that appeared to be stuck in the wall of a wood-panelled building.

About 28,000 people live in the Kongsberg municipality.

Following the attacks, the police directorate said it had ordered officers nationwide to carry firearms. Norwegian police are normally unarmed but officers have access to guns when needed.

-AAP