SANTA ANA, Calif. (AP) - An explosion in the boiler room of a Southern California high school has caused damage to a building but no students were injured.
    
Santa Ana Unified School District spokeswoman Deidra Powell told The Orange County Register (http://bit.ly/13UK6Yd) that the explosion Tuesday at Valley High School was near the gym and happened before classes began.
    
Security camera video broadcast by KABC-TV shows the explosion lift the building's roof.
    
Investigators with the Orange County Fire Authority are trying to determine if a gas line ruptured or if the boiler had a mechanical problem. A bomb squad was also called in as a precaution.
    
Fire Capt. Jon Muir says the building suffered significant structural damage.
    
Some classes near the blast were moved to other locations on campus.

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