Orange County Fire Authority Battalion Chief Scott Brown, right, confers with an investigator looking into a deadly explosion at Solus Industrial Innovations in Rancho Santa Margarita that also left two people injured. (Mark Boster / Los Angeles Times)
The front door area at Solus Industrial Innovations in Rancho Santa Margarita sustained damage in the deadly explosion. Arson investigators are looking for the cause of the late-night blast. (Mark Boster / Los Angeles Times)
Plant Manager Carl E. Richardson, center, talks with two representatives from Cal/OSHA after the deadly blast at the Solus Industrial Innovations plant in Rancho Santa Margarita. (Mark Boster / Los Angeles Times)
A chunk of concrete and other debris lie on the pavement at the Solus plant in Rancho Santa Margarita, where an industrial-sized electric water heater exploded Thursday night. The blast not only sent the water heater flying through the factorys roof but also damaged the wall. (Mark Boster / Los Angeles Times)