BERLIN - German police say that 25 people have been injured, four of them severely, when an explosion destroyed a building in the western city of Wuppertal.

Police say the explosion rocked the several-story building shortly before midnight Saturday with a large noise, scaring people in surrounding homes so much they ran out into the street in a panic.

Fire broke out in several different parts of the house and firefighters had trouble dousing the flames because parts of the building kept collapsing. 

Photos showed large parts of the facade and roof missing, as well as a car in the street that was completely crushed by the rubble.

Firefighters were able to rescue four severely injured from inside the building. Another 21 people were slightly injured and treated by emergency staff at the scene.

Police said Sunday they were still trying to get the fire under control. The cause of the explosion remains under investigation.

"How this came to pass and what the background is, that remains completely unclear," a police spokesman said.

DPA and AP