(CNN) -- An underground electrical vault exploded at a restaurant in Huntington Beach, California, Saturday, leaving four people injured.
The explosion took place during an Oktoberfest celebration at the Old World restaurant, where firefighters initially responded to a report of an electrical fire, Huntington Beach Fire Battalion Chief Jeffrey Lopez said. An underground electrical vault exploded as firefighters went to open it, Lopez said.
Video from witnesses shows a giant ball of fire erupting into the night sky. Witness Kyle Nelson told CNN affiliate KTLA-TV that he heard and saw three large explosions in rapid succession emanating from the festival. He managed to catch one of them on camera.
Huntington Beach firefighters worked to evacuate all of the restaurant's patrons and made sure the fire was under control, Lopez said.
Two firefighters and two civilians were injured in the explosion. All of the injuries are minor, Lopez said.
Fire investigators arrived on scene and are working with the Southern California Edison power company to investigate the cause of the explosion and whether gas had anything to do with it because some patrons had reported smells of gas, Lopez said.
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