"The events in Kongsberg appear at the present time to be an act of terrorism, but the investigation, which is led by South-East police district, will clarify further what events were motivated by. The threat level in Norway is still assessed as moderate," the service said in a statement.
Norwegian Police Security Service added that police continuously assesses the threat picture in Norway, and its assessment is that what happened in Kongsberg does not change the national threat picture.
On Wednesday evening, police detained a man in the centre of Kongsberg who opened fire with arrows, killing at least five people and wounding three more. The police are now treating it as a terrorist attack. It is known that the suspect, a 37-year-old Dane living in Kongsberg, acted alone.
The detainee was interrogated overnight.
According to the police, he admitted that he had committed what he was accused of, and expressed a readiness to cooperate with the police, but did not explain the motives behind the massacre.
Four women and one man were killed as a result of the Kongsberg, Norway bow and arrow attack; all victims were between 50 and 70 years old.