BERLIN (AP) — 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. They 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. They are investigating the cause of the explosion.