Updated

Norway said Thursday a bow-and-arrow attack that killed five people appears to have been an "act of terror" with the suspect, a Danish Muslim convert previously known over fears he had been radicalised. 

Four women and a man were killed, and three other people wounded during the rampage on Wednesday in the south-eastern town of Kongsberg in Norway's deadliest attack in a decade. 

"The events in Kongsberg currently appear to be an act of terror, but the investigation... will determine in closer detail what the acts were motivated by," Norway's intelligence service PST said.

Police official Ole Bredrup Saeverud told reporters the man was believed to be a Muslim convert, adding: "There were fears linked to radicalisation previously."

Saeverud said the 37-year-old suspect, identified by police as Espen Andersen Brathen, had confessed during questioning. 

Those who were killed during the attack were all aged between 50 and 70.

Reports that linked him to radicalisation pre-date this year, Saeverud said, and police followed up at the time. "We haven't had any reports about him in 2021, but earlier," he said.

"We're relatively sure that he acted alone."

PST also confirmed that the suspect was known to them but declined Thursday to release further details about him.

Norwegian media reported that Brathen was subject to two prior court rulings, including a restraining order against two close family members after threatening to kill one of them and a conviction for burglary and purchasing narcotics in 2012.

Threat level unchanged

Website Nettavisen published a video he allegedly posted to social media in 2017, in which he issued a "warning," while declaring his Muslim faith.

The PST security service said Wednesday's attack had not raised the general threat level in the country, describing it as "moderate".

"Our evaluation is that what happened in Kongsberg Wednesday October 13 does not change the national threat assessment," PST said.

It was the deadliest attack since far-right extremist Anders Behring Breivik killed 77 people in 2011. 

Since then, Norway has seen one other far-right attack, carried out by a self-proclaimed neo-Nazi who opened fire into a mosque.

Kongsberg, a picturesque town of 25,000 people with wooden facades and the foliage changing colour for the autumn, was largely quiet on Thursday.

Knut Olav Ouff, 54, told AFP he was about to light a cigarette on the doorstep when he found himself in the middle of the tragedy.

"I saw a friend of mine cowering behind a car and then suddenly heard a 'thung'," he said. "I could hear the tingling of the arrow hitting the streets. And after that I could see a man drawing a kid out of a car and running towards my house."

Streets were almost empty Thursday with only a light police presence.

A few police officers stood outside a store where part of the attack took place. A glass door there was chipped by a shot.

Two candles flickered outside the town's church.

'No smile, just staring'

A judge is due to rule on his custody on Friday after a psychiatric evaluation on Thursday, the prosecutor said.

The victims have not yet been named publicly, but one of the wounded was an off-duty police officer who had been in a store.

Norwegian media questioned why it took police more than a half-hour to arrest the suspect after the first reports of the attack.

Police were informed of the attack at 6.13pm (1613 GMT) and the suspect was arrested at 6:47 pm. He fired arrows at police, who responded with warning shots, Saeverud said.

Images in the media showed a black arrow sticking out of a wall and what looked like competition-grade arrows lying on the ground.

Police said Thursday the suspect had also used other weapons, but provided no details. 

A neighbour, who requested anonymity, decribed the suspect as a big person with short hair and a serious demeanor, who was always seen "alone".

"No smile, nothing in the face. He was just staring," the neighbour told AFP.

Norwegian police are not normally armed, but after the attack, the National Police Directorate ordered that officers be armed nationwide.

Norway rarely experiences such violence, but 10 years ago Anders Behring Breivik killed 77 people in the country's worst massacre since World War II.

Several planned jihadist attacks have also been foiled by security services.