40,000 People Under Evacuation Orders After Southern California Chemical Leak

Nearly 40,000 residents across six Orange County cities were under evacuation orders on Friday after a leaking chemical storage tank at a GKN Aerospace facility in Garden Grove triggered fears of a major explosion and toxic spill.

The crisis began on Thursday when a tank containing between 22,700 and 26,500 litres of methyl methacrylate (MMA) overheated and started releasing hazardous vapours. The chemical, used in aerospace plastics and acrylic products, is considered highly flammable, volatile and toxic .

Evacuations initially affected Garden Grove before expanding to parts of Cypress, Stanton, Anaheim, Buena Park and Westminster after crews failed to stabilise the tank overnight. Orange County Fire Authority Division Chief Craig Covey warned the tank had entered “thermal runaway” , meaning heat and pressure were continuing to build uncontrollably.

Officials said the tank could either rupture, spilling toxic chemicals, or explode and ignite nearby industrial tanks. Firefighters were remotely spraying water to cool the tank after a faulty valve complicated efforts to safely remove the chemical. Covey said the cooling operation had temporarily stabilised conditions and “bought time” for hazardous-material experts from across the United States to assist.

Authorities stressed there was currently no active toxic plume , though health officials warned MMA exposure could cause respiratory distress, dizziness, nausea and eye irritation. Air monitoring outside evacuation zones had not detected dangerous vapour levels.

Emergency crews built sandbag containment barriers to stop chemicals from reaching storm drains or waterways if the tank ruptures. Schools in affected areas remained closed, shelters were opened for evacuees, and officials said around 15 per cent of residents had refused evacuation orders.