May 16 (UPI) -- A blast at a California medical facility that killed a woman could have been caused intentionally by an explosive device, authorities said.
At least three others were injured in the explosion Tuesday at the Aliso Viejo, Calif., facility, which blew out walls of the two-story building.
Aliso Viejo is about 50 miles southeast of Los Angeles. The building was under construction and hadn't yet opened.
The Los Angeles Times reported investigators consider the blast suspicious, and may have resulted from a package delivered to the building. They don't know yet, though, if the act was intentional.
The Orange County Sheriff's Department said Wednesday investigators have not come to any firm conclusions.
"Investigation is in early stages," the department tweeted.
Officials originally believed the explosion was set off by a car crashing into the building, but a sheriff's spokeswoman said no car was involved.
The FBI has joined local authorities to determine the cause, but officials said there's no ongoing threat to the community.
Investigators didn't initially consider the explosion suspicious, and have so far found no explosive devices. The FBI said there was no indication of terrorism.