(CNN)Federal officials are responding after one person was killed Tuesday in an explosion at a medical building in Aliso Viejo, California.

Three people were injured in the blast, according to the Orange County Fire Authority. The explosion came from the inside out, and the first floor is heavily damaged. The walls and windows were blown out, Capt. Tony Bommarito said in an interview on CNN affiliate KCAL/KCBS.FBI spokesman Mike Gifford said there is no initial indication of terrorism.”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. Read MoreBraun said the two survivors had critical injuries “that were consistent with an explosion, but not necessarily consistent with a bomb.” The Federal Bureau of Investigations and the Bureau of Alcohol, Tobacco, Firearms and Explosives are responding, according a spokesperson from each agency. The initial call came in about an hour ago, at which point 10 engines and 70 firefighters were dispatched. There is a daycare and preschool nearby. Orange County Fire Authority Chief Brian Fennessy said no children were injured and all are accounted for.Aliso Viejo is about 7 miles northeast of Laguna Beach.

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