Investigators in Norway are provisionally classifying the attack by an archer with five dead as a suspected "act of terrorism".

The arrested suspect was the 37-year-old Dane Espen Andersen B., the police said on Thursday.

He is known to the police as a potentially radicalized Muslim.

However, his motive for the crime was still unclear, and the authorities initiated a psychiatric examination.

The attacker shot with a bow and arrow in several locations in the center of Kongsberg on Wednesday evening, including in a supermarket. He killed four women and a man between the ages of 50 and 70 and injured three other people. The suspect was arrested about half an hour after the crime. According to the police, he also used other weapons.

At this stage of the investigation, the attack had "the appearance of an act of terrorism," said the head of the PST, the secret service responsible for the fight against terrorism, Hans Sverre Sjovold, at a press conference.

The investigation would have to be pushed ahead to clarify the suspect's motive.

The police officer Ole Bredrup Saeverud had previously announced that B. had probably converted to Islam.

"There have been fears of radicalization before," Saeverud said.

However, these relate to 2020 and the years before that.

According to the police, the suspect made a confession during the interrogation.

His motive was still unclear.

"We're pretty sure he acted alone," Saeverud said.

A judge will decide on Friday whether B. will be in custody - presumably in the absence of the suspect.

Psychiatric examination could take "a few months"

A psychiatric evaluation of the man began on Thursday.

This could take "a few months", said prosecutor Ann Iren Svane Mathiassen.

The man's mental health may be an important question, said intelligence chief Sjovold, suggesting a medical history.

"For this person there was a back and forth in the health system for a while."

The secret service confirmed that he knew the alleged perpetrator, but did not provide any details.

According to media reports, there were two convictions against B: last year he was banned from visiting two relatives because of a death threat and in 2012 he was convicted of burglary and drug trafficking.

An eyewitness to the attack in Kongsberg, southwest of Oslo, told TV2 that she heard noise and then saw a woman take cover.

A man was standing on the corner with a bow in hand and a quiver of arrows.

"Then I saw people running for their lives," she reported.

The police leadership ordered that weapons be given to all officers across the country.

The majority of the Norwegian police officers are usually not armed.

Steinmeier and Maas upset and shocked

"We are shocked by these events," said the outgoing Prime Minister Erna Solberg.

Social Democrat Jonas Gahr Store took over government on Thursday after his party won the recent parliamentary elections.

Store, for its part, lamented the "terrible deeds".

Norway's King Harald was "appalled by the tragic events".

Federal President Frank-Walter Steinmeier stated in a letter of condolence that he learned of the “horrific act of violence” “with great dismay and deep sadness”.

Federal Foreign Minister Heiko Maas (SPD) said on Twitter that he was "shocked by the brutal attack".

Ten years ago, Norway experienced the worst attack in the country's modern history.

On July 22, 2011, right-wing extremist Anders Behring Breivik killed eight people with a bomb in the government district of Oslo.

He then crossed over to the island of Utöya and shot 69 people there, most of them participants in a summer camp for young people organized by the Labor Party.

Another attack hit the headlines in August 2019.

At that time, the racist Philip Manshaus carried out an attack on a mosque on the outskirts of Oslo.

Manshaus had previously killed his Asian-born stepsister.

Several Islamist attacks have also been foiled in the past.