'Number of people killed' in Oslo bomb blast: Police

Norwegian police say a number of people have been killed after a blast ripped through a building in the capital Oslo.

Windows were blown out and debris thrown into the streets below the building which houses the Norwegian government headquarters and the country's largest tabloid newspaper.

Norwegian news agency NTB said police confirmed a bomb caused the explosion.

Journalist Asgeuir Ueland is close to the scene of the explosion and says there are lots of walking wounded.

"We can still hear sirens coming and going from the area," he said.