The attacks took place in various locations in the city of Kongsberg, about 80 kilometers west of the capital Oslo
At least four people were killed and several others injured after a man armed with a bow and arrow rioted in a Norwegian city.
The attacks occurred in several different areas of Kongsberg city, police said tonight.
The officers arrested a man at one of the crime scenes, believing he was acting alone. The police said they are investigating whether the attacks were terrorist attacks.
Police chief Oeyvind Aas said: “The man was arrested … according to the information available to us, this person carried out these actions alone.
“Several people were injured, several are dead.”
He declined to comment on the exact death toll, but Norwegian public broadcaster NRK later reported that police sources had said at least four people had died.
Officials cordoned off parts of the city and ordered residents to stay inside.
Arrows could be seen in the streets.
Police said the attacks took place over “a large area” of Kongsberg, a town of around 28,000 people about 80 kilometers west of Oslo in the south-east of the country
According to media reports, the attacker opened fire in a Coop-Extra supermarket in the west of the city.
Dozens of emergency vehicles were on site when the injured were taken to the hospital.
The suspect is said to have been taken to a police station in the city of Drammen.
The Norwegian Justice and Security Minister Monica Maeland has learned about the incident and is expected to monitor the situation closely.
This story will be updated