Police have found undetonated explosives on an island where a gunman killed at least 10 people at a youth camp near Oslo, local media reports said.
Deputy Oslo police chief Sveining Sponheim, who spoke to journalists in Oslo, has not provided further details on the explosives found.
Police have identified the gunman, who was arrested after the shooting at the Labor Party youth camp, as a 32-year-old ethnic Norwegian. They believe the man was also behind Friday's bomb attack on a government headquarters in the capital of Oslo, which killed at least 7 people and injured at least 19.
Police sources were quoted by media reports as saying that the man was not likely to be linked to any international terrorist organizations. The TV2 channel quoted sources as saying the arrested belonged to right-extremist groups in eastern Norway.
The TV channel quoted its reporter on the spot as saying police had searched the man's house to the west of Oslo late on Friday