Candles and flowers are laid outside the Extra grocery store to honour the dead, after a man killed five people in the city on Wednesday night, in Kongsberg, Norway. Image Credit: Reuters

Kongsberg: The man who killed five people in a bow-and-arrow attack in Norway this week has been handed over to health services, the prosecution said Friday, fuelling doubts about his mental health.

"He was handed over to health services on Thursday evening after an evaluation of his health condition," prosecutor Ann Iren Svane Mathiassen told AFP.

Doubts have arisen about the mental health of the attacker and whether he can be held legally responsible for his actions.

Identified as Danish citizen Espen Andersen Brathen, he converted to Islam and is believed to have been radicalised. He has confessed to the killings.

A psychiatric evaluation began on Thursday, which was expected to take up to several months.

Meanwhile, a judge was to decide later Friday whether to hold Brathen in detention. The prosecution has asked for him to be held for four weeks, the first two in isolation.

If the judge grants the prosecution's request, he would not be jailed but rather held in medical care, the prosecutor said.

While police have said the attack was probably an act of terror, authorities have not ruled out the possibility of mental health problems.

"There is no doubt that the actual act appears as if it could be an act of terror, but it's important that the investigation continues and that we establish the motive of the suspect," the head of Norway's intelligence service PST, Hans Sverre Sjovold, told a news conference on Thursday.

"This is a person who has been in and out of the health system for some time," Sjovold said.

He has confessed to killing five people and injuring three in the south-eastern town of Kongsberg, using a bow and arrows and other undisclosed weapons before police managed to arrest him.

'No smile, just staring'

The suspect was known to PST, which is in charge of Norway's anti-terrorism efforts, but few details have emerged about why.

"There were fears linked to radicalisation previously," police official Ole Bredrup Saeverud told reporters.

Those reports were before this year, and police had followed up at the time.

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

Local media also unearthed a video Brathen allegedly posted to social media in 2017, in which he issued a "warning" and declared his Muslim faith.

Brathen is believed to have acted alone when he killed four women and a man, aged between 50 and 70, in several locations in Kongsberg where he lived.

The picturesque, tranquil town of 25,000 people is located about 80 kilometres (50 miles) west of Oslo.

Speaking anonymously, one of Brathen's neighbours described the suspect as a big person with a crew cut and a serious demeanour, who was always seen "alone".

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

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 been foiled by security services.