A woman was killed and three other people were hurt Tuesday in what investigators believe was an intentional explosion at a California building housing medical offices. A federal official tells the AP that a preliminary investigation of the building in Aliso Viejo, around 50 miles south of Los Angeles, suggests the explosion was caused by a parcel bomb. Authorities initially thought the blast, which blew out doors and windows on the building's bottom floor, had been caused by a car smashing into the building. A day care center across the street from the building was evacuated.
It's not clear what, if anything, could have made the building a target. The Los Angeles Times reports that the building's tenants include a massage business, a medical practice, and at least one chiropractor's office. The woman killed was very close to the source of the blast, officials say. Orange County Fire Authority Capt. Tony Bommarito says one of the wounded people had smoke inhalation injuries, the Orange County Register reports. Agents from the Orange County Sheriff's Department, the FBI, and the ATF were at the scene Tuesday night, along with bomb technicians. (Read more California stories.)