LOS ANGELES (AP) -- Investigators are searching for clues about an explosion at a Southern California medical office that left a woman dead and three other people injured.
The Tuesday afternoon blast occurred in Aliso Viejo, which is about 50 miles south of Los Angeles. It blew siding off the walls, exposing insulation and framing and shattering windows at the two-story building.
A federal official told The Associated Press late Tuesday that the explosion is believed to have been intentional and may have come from a package.
Authorities say the dead woman had been inside the building.
A witness, Mary McWilliams, tells the Orange County Register that she saw two burned women stagger from the building. Fire officials say a third victim had smoke inhalation.
There's no word yet on a motive for the explosion.