The attack was carried out in the town of Kongsberg, southwest of the capital Oslo, at 18:13 local time (16:13 GMT), the police said in a statement issued early on Thursday.

“Five people were killed after a serious incident at Kongsberg on Wednesday night. Two people were injured and sent to the hospital for treatment. One of the injured is a police officer who was at the scene at his leisure,” the statement said.

The police arrested the perpetrator, a 37-year-old Danish citizen living in Kongsberg, according to the statement.

Norwegian Prime Minister Erna Solberg described the incident as “horrifying”.

“It is too early to say anything about the motive behind the actions but police are considering whether it is a terrorist act,” she told a news conference.