A French fireman and his dog search the rubble of a building after an explosion caused it to collapse, in Rosny-sous-Bois, outside Paris on Sunday.

French authorities say the four-story building’s collapse killed a child. More people were thought to be underneath the rubble.

Fire department spokesman Gabriel Plus said around 10 people evacuated the building in Rosny-sous-bois early Sunday. Plus said that about 10 more could still be underneath the rubble, and emergency teams were working hard to rescue people who might be trapped.

“We could still find living victims in the hours to come,” he said. Interior Minister Bernard Cazeneuve had arrived at the scene, but couldn’t confirm a theory that the explosion was caused by a gas leak.