The explosion at the office building in Aliso Viejo - about 50 miles (80.5 kilometers) south of Los Angeles - blew siding off the walls, exposing insulation and framing.
The explosion occurred at about 1 p.m. and caused damage to the first floor of the two-story building, which was under construction.
A USA official told the Associated Press the authorities were investigating it as an intentional act and a package may have caused the blast.
Officials didn't consider the explosion suspicious and they found no explosive devices.
He said authorities believe the explosion came from inside the building, since the doors and windows on the bottom floor were "blown out", according to The Register.
The FBI is responding to the scene, a law enforcement official told CBS News senior investigative producer Pat Milton.
"We are still trying to determine if this explosion was accidental or intentional", said Carrie Braun, a spokeswoman for the Orange County Sheriff's Office.
Mariners, Tigers split doubleheader
The Tigers had 12 hits; Seattle starter Marco Gonzales (3-3) allowed 10 hits and all four runs in six innings. Cano was struck by an 88 miles per hour fastball from left-hander Blaine Hardy in the third inning.
There were unconfirmed initial witness reports that the blast may have been a gas explosion, but Bommarito said it is rare for such gas-fueled blast to occur in a commercial building.
Three people were injured in the blast, according to the Orange County Fire Authority.
One person was pronounced dead at the scene, and three others were injured, OCFA said.
There was no initial indication of terrorism, according to the Federal Bureau of Investigation.
Mary McWilliams told the Orange County Register that she arrived for an appointment to find smoke surrounding the area and vehicle alarms going off. The other woman was burned and her head was bleeding.
"... They weren't on fire, they were helping each other across the street, walking very slowly and a lot of shock, shaking, just full of ash all over their face, eyes bloodshot, just blood all over", the woman said. Still, they chose to evacuate a nearby day care and other surrounding businesses as a precaution.
Of the three people who were injured, Ms. Braun said, two suffered "significant" injuries while the third complained of smoke inhalation.
Kim revealed plans to shut down the nuclear test site during his summit with South Korean President Moon Jae-in last month. However there was no mention of allowing foreign experts access to the site in Saturday's statement from North Korea.
Mom told us she approved of the people we chose to marry and pulled no punches when she thought we were making bad decisions. By 1914 a measure was signed by the president which officially established the second Sunday in May as Mother's Day . "6.
According to reports, several shops and vehicles were damaged in the Chelipura and Motikaranja areas of Aurangabad also. Speaking on the issue, state Home Minister appealed to "maintain peace and urged to not believe in rumours".
Other T-shirts in the range show San Francisco, Paris, Japan and Canada but are decorated with national flags rather than maps. Gap quickly apologized, even though it appears the T-shirt is not for sale in China .
The Russian bombers never entered U.S. airspace, the spokesman for the North American Aerospace Defense Command told CNN . NATO naval officials in late 2017 also reported Russian submarines probing underseas data cables in the North Atlantic.
The top Democrat on the Senate intelligence committee says he will vote to confirm Gina Haspel to be the next CIA director. But critics have said she should have been more forceful in denouncing torture and Mr.
Ryan told the Eurovision cameras backstage how it was impossible to describe the feeling of being called up for the final. The Czech Republic's Mikolas Josef has progressed to Saturday's final of the Eurovision Song Contest in Lisbon.
Oil price nears $80
The tightening market has just about solved the global supply overhang that has weighed down oil prices between 2014 and 2017. Iran now provides approximately 4 percent of global crude supplies and is the third-biggest manufacturer in the OPEC.
New York School Districts Brace for Budget Votes
Newsday's annual survey of district spending plans found wide disparities in approach from one community to another. In New Rochelle, the budget will need at least 60 percent of voters to approve the spending plan in order to pass.
'Perfect' drive gives Power IndyCar GP win
Four straight pole winners have won the race, including Power, who has won all three from the No. 1 starting position. James Hinchcliffe will start in fourth to give Schmidt-Peterson a strong outlook heading into Saturday's Grand Prix.
Woman to be executed for killing man during rape
Shahd Hamza, 20, was among those who came to support Hussein in court, after hearing about her case in a group chat on WhatsApp. Forced child marriage and marital rape are not considered crimes in Sudan, and can not be used as evidence in a defence.