Police say they are sending anti-terror police to a youth camp outside Oslo after reports of a shooting there following the bomb blast at the government headquarters.

The news site VG reported that a man dressed in a police uniform opened fire at the camp. It says several people were injured.

Oslo police Chief Anstein Gjengdal said anti-terror units were being sent to the camp at Utoya, outside the Norwegian capital.

He had no other information on that incident, which came hours after a bomb blast outside the government headquarters killed at least 7 people and injured 15.