A large explosion in central Oslo rocked the Norwegian government headquarters on Friday, killing at least one person and injuring several others.

The powerful blast also set the nearby oil ministry building on fire. Hundreds of windows in the 17-story government headquarters and other buildings as far away as 400 meters away were shattered. Smoke billowed from some of the offices and streets in the normally quiet neighborhood were littered with debris from the explosion.

The headquarters building houses the office of Prime Minister Jens Stoltenberg, but a Norwegian spokesman said he and his staff were not injured by the mid-afternoon explosion. News agencies reported at least one person was killed.

Oslo police said the explosion was caused by a bomb. The tangled wreckage of a car could be seen outside one building, possibly indicating a car bomb had been detonated.

Witnesses said they saw several injured people covered with blood as they were carried or ran from the government building, with a Reuters correspondent saying he saw at least eight injured people. One witness said “people ran in panic.”

The government headquarters is located in what several Norwegians said is a normally peaceful neighborhood.

Political violence is virtually unknown in Norway.