FRESNO, Calif. (FOX26) — A former Fresno firefighter is now at the center of a major hazardous materials emergency in Southern California after a tank containing methyl methacrylate overheated Thursday at an aerospace facility, prompting evacuations for thousands.

Officials said a few hours ago that the threat of an explosion is gone, but evacuation orders remained in place.

Assistant Chief Chuck Tobias, who served as a Fresno firefighter for 36 years, is now leading California’s Office of Emergency Services operation as a hazmat specialist.

Tobias said the damaged tank in Garden Grove overheated and contained a hazardous, flammable chemical used to make windshields for aircraft.

Officials initially feared two possible outcomes. “The first option we were informed of was a catastrophic failure of the tank with an explosion and fireball, which would have significantly impacted the entire community,” Tobias said. “Second option would have been a catastrophic failure of the tank, releasing the product, which is flammable, into the property operating in a storm drain,” he said.

Tobias said he assembled a team of hazmat experts to develop another approach. “Our purpose was to get together within an hour and a half; we had the third solution nailed down that we’re moving with now,” he said.

That plan required crews to peel back the tank’s outer shell and insulation so water could cool the tank and the chemical inside. “We were able to bring the temperature of that takedown significantly, so it’s no longer posing a threat for explosion,” Tobias said. “And now our next portion is to get the product out of the tank, and we’re coming up with solutions for that now.”

Tobias said his experience in Fresno helped prepare him for the response. “A Fresno is a very busy community, so there’s a lot of different types of disasters, little mini disasters that occur,” he said. “When I retired from there, I got recruited to go work with the state. To build a hazmat program.”

The cause of the overheating has not been determined, but Tobias said the cooling system may have failed. He said discussions are underway with regulatory agencies about preventing a similar incident in the future, including the U.S. Environmental Protection Agency, Cal EPA, and the Department of Toxic Substances.

Gov. Gavin Newsom announced today that President Trump approved California’s request for a presidential emergency declaration to support ongoing emergency response operations.