According to police, a man killed several people with a bow and arrow in the Norwegian city of Kogsberg.
In addition, there are injuries, said the local police on Wednesday evening.
The act took place in the center of the city of Kongsberg, southwest of Oslo.
"The man was arrested," police chief Oeyvind Aas told reporters.
"According to our information so far, he carried out the acts alone." He initially gave no information about the number of victims.
The background was initially unclear.
According to the police, it was still too early to answer the question of whether it could have been a terrorist-motivated act.