Unoccupied house explodes in Riverside, Calif.

RIVERSIDE, Calif., Sept. 6 (UPI) -- Investigators were trying to determine what caused an explosion Friday that gutted an empty house in Riverside, Calif., and damaged neighboring homes.

No one was killed or injured, KABC-TV, Los Angeles, reported. The blast at about 4 a.m. woke the neighborhood, sending residents fleeing into the street.

Neighbors said the house that blew up was under construction. Officials said it was possible the explosion was caused by a gas leak.

Wayne Keller told KABC his house, near the one that exploded, is now uninhabitable. But he said he, his wife and their dogs all got out safe.