Authorities said an explosion Thursday near a Santa Monica synagogue was an industrial accident.
Investigators said a chemical reaction caused the blast, which occurred in a bin filled with construction debris. The bin was between the Chabad House and a guest house near the synagogue.
The blast sent a pipe from the bin onto the roof of the guest house. The pipe left a hole in the roof of the building in the 1400 block of 18th Street.
Someone was trying to remove a large pipe that was stuck in concrete near an alley but the chemical mixture they used created pressure and launched the 4-foot-long pipe and plug of concrete into the air, fire Capt. Mark Bridges said.
"The device lifted up off the ground approximately 25 feet, punched a hole in the (Chabad House) and then ricocheted,'' Bridges said.
About 100 people were evacuated from nearby homes as bomb experts investigated. Streets were closed, but authorities reopened nearby roads at about 11:30 a.m.
No injuries were reported.
Santa Monica police said the explosion was not a type of bomb. Sgt. Marty Fine told the Associated Press that some kind of device hit the roof of a building and exploded at about 6:45 a.m. Thursday.
The AP reported that FBI agents and LA County Sheriff's bomb experts are at the site.