VALLEY CENTER, Calif.—A woman's burned body was found in the footprint of a small brush fire, officials said.

Firefighters discovered the woman's remains near a migrant encampment as they worked to put out the fire early Wednesday morning, according to California Department of Forestry and Fire Protection dispatcher Larry Craig.

Pieces of an exploded propane tank were found near the body, said sheriff's Sgt. Conrad Grayson of the bomb and arson unit.

Residents in the hilly, rural area 45 miles north of San Diego reported hearing an explosion before the fire broke out.

"We were all woken up," said Marge Sullivan. "It was loud. It's usually pretty quiet out here."

Sheriff's investigators said they do not yet know whether the woman was killed by the fire. Foul play has not been ruled out, according to Sheriff's Sgt. Ed Wells.

The woman's identity has not been released.

The fire burned less than an acre in an open area, fire officials said.