Thousands evacuated as overheated chemical tank threatens explosion in Garden Grove

Thousands of people were ordered out of their homes in Garden Grove and surrounding Orange County cities after firefighters said they could not safely intervene with an overheated chemical tank that was close to collapsing or exploding. The emergency centered on a 34,000-gallon tank at GKN Aerospace, where authorities said the most realistic outcomes were a spill of about 6,000 to 7,000 gallons into the parking lot or a thermal runaway event that could trigger an explosion and threaten nearby fuel and chemical tanks.

Firefighters first responded Thursday afternoon, May 21, to a vapor release from the tank, which contained methyl methacrylate, a volatile chemical used to make acrylic plastics and Plexiglass. Officials later said the tank had overheated and the valve had become inoperable, leaving crews unable to secure it or remove the chemical. Water was being used to cool the tank, but an agent intended to neutralize the chemical had not worked, underscoring how a storage failure inside an industrial facility turned into a neighborhood-scale public safety crisis.

By Friday, May 22, the evacuation zone had expanded to cover about 40,000 people in parts of Garden Grove, Cypress, Stanton, Anaheim, Buena Park and Westminster. Over a dozen schools were temporarily closed, and some outdoor activities were canceled as districts moved to keep students away from the area. Garden Grove Unified School District said schools outside the evacuation area were safe, while activities near the perimeter were halted out of caution. Reunification services for evacuees were set up at Rancho Alamitos High School.

Orange County Fire Authority officials said there was no active gas leak or plume during Friday’s briefing, but they also described the situation as unlike a routine industrial fire because the tank’s condition could not be predicted with confidence. The U.S. Environmental Protection Agency assisted with air monitoring as crews tried to manage the site without provoking a worse release. Methyl methacrylate can irritate the lungs, skin, eyes, nose and throat, and the chemical is highly flammable, adding to the danger for nearby homes, schools and businesses.

The evacuation order was first lifted Thursday night after vapor conditions improved, then reinstated and expanded early Friday morning when conditions worsened again. No injuries had been reported as of Friday, but the incident exposed a harsh reality of dense urban-industrial borders: when a toxic tank overheats and its valves fail, firefighters may be left with no safe intervention at all.