A fire swept through a single-story home in southern Indiana on Sunday morning, killing at least four people, State Fire Marshal Roger Johnson said.

The fire was reported about 9:35 a.m., and Johnson said there may be other victims inside the still-burning structure.

"We don't know if there are any more in there. They're still searching and the building's still on fire," he said.

There was no immediate word on how the fire started.

The fire occurred at a home near the downtown area of North Vernon, about 50 miles south of Indianapolis.