40,000 evacuated in Southern California as chemical tank risks rupture

About 40,000 people were ordered out of neighborhoods across Orange County after a chemical tank at GKN Aerospace in Garden Grove stayed unstable enough that officials warned it could rupture or explode. Schools shut down Friday, campuses were evacuated in some districts, and outdoor activities were canceled as the danger spread from Garden Grove into parts of Cypress, Stanton, Anaheim, Buena Park and Westminster.

The tank, at the aerospace plastics facility on Western Avenue, held methyl methacrylate, a volatile, flammable liquid used to make resins and plastic parts, including components for commercial and military aircraft. Officials said it was first reported leaking Thursday afternoon after overheating and venting vapors. The tank was estimated to hold about 6,000 to 7,000 gallons of chemical, though some reports described a 34,000-gallon tank with roughly 7,000 gallons inside.

Orange County fire officials said the tank had bulged and that crews could not safely access or move the material because of a damaged valve. They said the worst-case scenarios included a sudden rupture that could spill thousands of gallons or a thermal event that could trigger a boiling liquid expanding vapor explosion. Officials also said they were using sandbag barriers to keep any release from reaching storm drains, creeks or the nearby ocean.

Health officials warned that even short-term exposure to methyl methacrylate vapor can irritate the lungs and nasal passages and can cause nausea and dizziness. Higher exposures can lead to severe respiratory distress and hospitalization. By Friday, authorities said there was no active gas leak or chemical plume in the area, but they kept the evacuation orders in place because the tank remained unstable and could fail without warning.

Garden Grove Fire Chief Craig Covey said crews had neutralized one damaged tank, but the remaining one was in the “biggest crisis” of the incident, which he described as one of the most dangerous events of his 32-year fire-service career. Garden Grove Mayor Stephanie Klopfenstein told residents the evacuation orders were for their safety. County Superintendent of Schools Dr. Stefan Bean said districts were making fast-moving decisions to protect students, families and staff, while county health officer Dr. Regina Chinsio-Kwong outlined the exposure risks.

Officials said state and national experts were helping search for a way to depressurize the tank and stabilize the scene, but there was no firm timetable for lifting the orders. For thousands of families, the leak did more than threaten an industrial site: it froze daily life across a swath of suburban Orange County until the tank could be secured.