The suspect in the bow and arrow attack in Norway that left five dead had been singled out for possible signs of radicalization, police said.
Officers were concerned by signs that the man, who was a Muslim convert, may have been radicalizedsaid Police Chief Ole Bredrup Saeverud at a news conference.
The 37-year-old Dane is in custody.
According to prosecutor Ann Iren Svane Matthiassen, she admitted to having carried out the attack on Kongsberg, wounded southwest of the capital Oslo, which also left two others.
The death toll was the worst of any attack in Norway since 2011, when far-right extremist Anders Behring Breivik killed 77 people, mostly teenagers, in a youth camp.
Police were first alerted to the events in Kongsberg at 6.15pm local time, and a suspect was arrested half an hour later.
Several of the victims were in a supermarket when they were attacked.
A spokesperson for Coop supermarkets said: “We can confirm that there has been a serious incident at our store and that none of our employees have suffered physical injuries.”
“Now we are concerned with following up on our employees, and beyond that, we refer to the police investigation.”
The two people who were injured were taken to intensive care, and one was an off-duty police officer who was in the supermarket at the time.