A failing electric water heater exploded at a plastics manufacturing plant, killing two people and injuring two others, officials said Friday.

Isidro Echeverria, 34, of Oceanside, and Jose Jimenez, 51, of Garden Grove, died in the blast late Thursday at Solus Industrial Innovations in Rancho Santa Margarita, the Orange County coroner's office said.

The force of the blast blew out a concrete wall in the plant. Damage to the building and its contents was estimated at $1.5 million, said Capt. Greg McKeown, a spokesman for the Orange County Fire Authority.

Firefighters from a nearby firehouse who heard the explosion rushed over and found two bodies, he said.

Two workers were taken to Mission Hospital with minor injuries, McKeown said.

Dave Baldridge, a Solus spokesman, said the company was setting up an employee assistance program to provide counseling to workers.