Authorities named the suspect as Espen Andersen Bråthen, 37, and said he is a Muslim convert who had previously been flagged as radicalized.
“Before, there had been concerns that the man had become radicalized,” Police Chief Ole B Saeverud told a news conference on Thursday.
Norway’s national security agency said the suspect’s actions “currently appear to be an act of terrorism.”
Five people were killed and three injured during the riot in the small town of Kongsberg on Wednesday night.
Police revealed Bråthen’s identity after giving more information about him. victims, revealing that there were four women and a man between 50 and 70 years old.
The suspect is believed to have shot people at various locations in the city. Policeman They were called to the city center, southwest of Oslo, after the attack began at around 6.15pm.
Authorities believe the man did not start killing people until police arrived at the scene.
“From what we know now, it is reasonably clear that some, probably all, died after the police contacted the perpetrator,” Saeverud said.
Speaking calmly and clearly after his arrest, the suspect told police: “I did this,” according to a witness.
In addition to the five dead, two others remain in intensive care, including an officer who was off duty and inside the store where the attack took place, police said.
“The man who carried out the act has been detained by the police and there is no active search for more people. According to the information we have, there is a person behind this, ”said Police Chief Oeyving Aas.
Police said Bråthen lived in Kongsberg. They also said that additional weapons were used in addition to the bow and arrow.
The police chief confirmed that there was a confrontation with the suspect when he tried to flee before being arrested.
Kongsberg City Mayor Kari Anne Sand saidTV 2 which was “a ghastly incident”.
“There’s nothing more to say. Now we must try to take care of the inhabitants as best we can ”.
Prime Minister-designate Jonas Gahr Stoere, who is expected to take office on Thursday, called the assault “a cruel and brutal act” in comments to the Norwegian news agency. NTB.
Authorities said they had immediately ordered officers across the country to carry firearms. The Norwegian police are normally unarmed, but officers have access to guns and rifles when necessary.
“This is an additional precaution. The police have no indication so far that there is a change in the level of national threat, ”the management said in a statement.
The attacks took place in “a large area” of Kongsberg, a municipality of about 28,000 people 66 km (41 miles) southwest of Oslo, including at a Coop Extra grocery store, the Aftenposten The newspaper quoted the police as saying.
A woman who lives near the store said she heard alarms while walking home.
“I saw a group of policemen, including one who was holding several arrows in his hand,” the woman, Marit Hoefle, told the newspaper.
Erik Benum, who lives on the same street as the supermarket that was one of the crime scenes, told the AP who saw runaway store workers taking refuge in the gates.
“I saw them hiding in the corner. Then I went to see what was happening and saw the police coming in with a shield and rifles. It was a very strange sight. ”
The death toll was the worst of all attacks in Norway since 2011, when far-right extremist Anders Behring Breivik killed 77 people, mostly teenagers, in a youth camp.
Kongsberg’s main church was open to anyone in need of support on Thursday.
“I don’t think anyone expects to have these kinds of experiences. But no one could imagine that this could happen here in our small town, ”said Pastor Reidar Aasboe.