The emergency centers on a tank at GKN Aerospace containing approximately 7,000 gallons of methyl methacrylate, a highly flammable and volatile chemical commonly used in plastic manufacturing.

According to Orange County Fire Authority incident commander Craig Covey, the leaking tank poses an ongoing danger due to rising internal temperatures and the possibility of a Boiling Liquid Expanding Vapor Explosion (BLEVE), one of the most dangerous types of industrial explosions.

Firefighters conducting overnight operations reportedly discovered what may be a crack in the tank, which officials believe could be relieving some internal pressure. Orange County Fire Authority interim chief T.J. McGovern described the development as “a step in the right direction,” while warning that the threat had not yet been eliminated.

Emergency crews equipped with hazardous materials training entered the danger zone Sunday night to directly inspect the tank and assess whether the pressure could be safely reduced.

“It’ll be an all-night mission in order to confirm that the pressure in the tank has been released and that the BLEVE threat is eliminated,” McGovern said, stressing that authorities were still confronting a potentially catastrophic situation.

The Federal Emergency Management Agency and the Environmental Protection Agency are both assisting in the response operation. FEMA said a malfunctioning valve on the tank remains unresolved while the chemical reaction inside continues without a reliable method to neutralize it.

Authorities said two nearby tanks at the facility were also impacted but remain structurally stable.

Mandatory evacuation orders affecting roughly 50,000 residents remain in place around the affected industrial area. Officials urged the public to stay away from evacuation zones to allow emergency operations to continue safely.

California Governor Gavin Newsom declared a state of emergency for Orange County, stating that state resources were being mobilized to support local responders and protect residents.

Experts warn that methyl methacrylate presents severe fire and health risks. The chemical is highly flammable and capable of generating heat independently, meaning even a small spark could trigger a major fire or explosion if vapors escape into the atmosphere.

Elias Picazo, an associate professor of chemistry at the University of Southern California, said exposure to the chemical can cause respiratory irritation, dizziness, nausea, and irritation to the skin and eyes.

Authorities previously believed temperatures inside the tank were stabilizing, but later discovered that temperatures were continuing to rise by approximately one degree per hour. Officials reported that the tank’s temperature exceeded 100 degrees by Saturday night — more than double the safe operating range for the substance.

Covey described the incident as the most dangerous event he has encountered in decades of fire service.

“This is as bad as I’ve ever seen,” he said.

Officials outlined two possible scenarios if the situation worsens: the tank could rupture and spill thousands of gallons of hazardous chemicals, or it could explode and send dangerous chemical particles into the air, potentially affecting surrounding tanks containing fuel and other industrial substances.

Emergency crews have built containment barriers using sandbags to prevent any leaked chemicals from reaching storm drains or nearby waterways.

Despite the scale of the emergency, authorities confirmed that no injuries or deaths had been reported as of Sunday night.

The cause of the leak remains under investigation. (ILKHA)