The police said that they had previously contacted the suspect, a 37-year-old Danish citizen who is believed to have killed five people, over concerns that he had been radicalized.

A 37-year-old man was charged on Thursday in connection with a bow-and-arrow rampage in a small town in Norway that killed five people and wounded three others, in what the authorities said was an apparent act of terrorism.

In a statement, the police identified the suspect as Espen Andersen Brathen. The Norwegian security agency, known by its acronym, PST, said investigators were still trying to determine what motivated the attacker to carry out his grisly assault in the town of Kongsberg, about 50 miles southwest of Oslo.