Federal officials are responding after one person was killed Tuesday in an explosion at a medical building in Aliso Viejo, California.
A US official says a deadly explosion at a Southern California office building is being investigated as an intentional act and investigators believe the blast may have come from a package.
Authorities have not yet found explosive devices in the area, according to officials.
Bomb squad investigators and FBI agents were looking into the cause of the blast Tuesday.
Authorities have said that there is no lingering threat to the public, and there didn't initially appear to be any threats made before the blast or signs of terrorism.
A daycare and preschool are near the site of the explosion, but authorities say all of the children are safe.
Officials originally believed the explosion was caused by a vehicle crashing into the building, but Orange County Sheriff's Department spokeswoman Carrie Braun said no auto was involved and the department was investigating how the explosion occurred.
Gap apologises for China map T-shirt that didn't show Taiwan
It also apologised for "this unintentional mistake and is now conducting internal investigations to quickly rectify this mistake". Mercedes-Benz said sorry for quoting the Dalai Lama on social media.
The powerful blast blew out almost the entire bottom floor, officials said.
Although the cause of the blast was still unknown, Bommarito told reporters around 3:30 p.m. that there was "no immediate hazard" to the community.
"Take care of my mother, take care of my mother!" shouted one woman as she fled, according to NBC4.
Officials declared a second-alarm fire and hazmat situation, and crews successfully extinguished a fire at the building after the explosion. The other woman was burned and her head was bleeding.
Shin said he and others hurried down the stairs to get out of that building, and saw "two holes in the wall" of the medical facility.
Orange County Fire Authority Chief Brian Fennessy says 70 firefighters were dispatched in response to a 1:09 p.m. Tuesday call from Aliso Viejo.
Of the three people who were injured, Ms. Braun said, two suffered "significant" injuries while the third complained of smoke inhalation. They expected a lengthy investigation to determine the cause.