The man who killed five people with a bow-and-arrow and other weapons in Norway was probably suffering from mental illness, police said on Friday, APA reports quoting Reuters.
The attacker went on a half-hour rampage in the southern town of Kongsberg on Wednesday, assaulting people in the streets and forcing his way into houses and one supermarket.
Police arrested a suspect the same day - Espen Andersen Braathen, a 37-year-old Danish citizen who has lived in Kongsberg for most of his life.
Officers had looked into several lines of inquiry, including "anger, revenge, impulse, jihad, illness, provocation," police inspector Per Thomas Omholt told a news conference.
"The hypothesis that has been strengthened the most in the first days of the investigation is that the background is illness," Omholt said.
The suspect was being held in a locked "psychiatric institution" and other lines of inquiry were still being pursued, he added.
Four women and one man aged between 50 and 70 were killed in the attacks in Kongsberg, a town and municipality about 70 km (40 miles) west of the capital, Oslo. Three people were wounded including an off-duty police officer.