Two men were killed and two others injured when an industrial-sized electric water heater exploded in a Rancho Santa Margarita plastics factory.
The blast at about 11:40 p.m. Thursday was of such force that it shot the water heater through the roof of the south Orange County facility. It then came crashing down inside the building.
Killed were Isidro Echeverria, 34, of Oceanside and Jose Jimenez, 51, of Garden Grove. Two other men were taken to a hospital with minor injuries, authorities said, while two others refused treatment.
The men were working the night shift at Solus Industrial Innovations, which manufactures and distributes conveyors, conveying equipment, plastic belts and other products.
Firefighters at a station across the street heard -- and felt -- the blast. But the explosion didn't cause a fire.
"One of the guys there described it like a truck had hit the station, just the force from the blast across the street," said Orange County Fire Authority Battalion Chief Kris Concepcion.
Arson investigators on Friday were trying to determine the cause of the explosion, which blew chunks of concrete into the air and buckled the walls of the building at 30152 Aventura Ave.
"We deeply regret that two of our employees were killed in the accident," said Dave Baldridge, a Solus spokesman. "We extend our deepest sympathies to their families, and we will provide all support possible to them during this difficult time."