GKN Aerospace Chemical Incident: A Multi-Day Emergency Unfolds
Garden Grove, CA — On Thursday, May 21, 2026, a storage tank containing methyl methacrylate (MMA) at a GKN Aerospace facility began overheating, triggering a multi-day emergency response, large-scale evacuations, and a state of emergency declaration.
Incident Overview
The incident occurred at the GKN Aerospace facility located at Western and Lampson avenues. The tank, with a total capacity of 34,000 gallons, contained an estimated 6,000 to 7,000 gallons of methyl methacrylate, a volatile, flammable liquid used in the production of acrylic plastics and resins.
On Thursday afternoon, the tank's cooling system failed, causing the chemical to heat up and vent vapors. Valves on the tank became inoperable, preventing the addition of a stabilizing chemical or the controlled drainage of the tank. The chemical's exothermic polymerization process—a heat-releasing reaction—was identified as a contributing factor to the escalating temperatures.
"The tank was 'actively in crisis'…" — OCFA Division Chief Craig Covey
Evacuation Orders
Initial evacuation orders were issued on Thursday and later rolled back. On Friday, orders were reissued and expanded as the threat of a tank failure or explosion increased. The evacuation zone eventually covered a one-mile radius affecting parts of Garden Grove, Anaheim, Buena Park, Cypress, Stanton, and Westminster.
- Affected Population: Estimates varied between 40,000 and 50,000 residents.
- Shelters: Evacuation centers were established at Stanton City Hall (7800 Katella Ave.), the Garden Grove Sports & Recreation Center (13641 Deodara Dr.), and other locations in Cypress. Some shelters reached capacity.
- Compliance: Garden Grove Police Chief Amir El-Farra reported that approximately 15% of residents in the evacuation zone initially refused to leave.
- Closures: The Garden Grove Unified School District closed 15 campuses until further notice. A vote center was closed to serve as a shelter. The Garden Grove Strawberry Festival's 5k marathon and parade were canceled, though the festival itself proceeded.
Response and Mitigation Efforts
The Orange County Fire Authority (OCFA) led the response, supported by state agencies and the U.S. Environmental Protection Agency (EPA).
Cooling Operations
Fire crews continuously sprayed the tank with water from unmanned hoses and sprinklers. While this successfully reduced the tank's external temperature, the internal temperature continued to rise for a period, increasing by approximately one degree Fahrenheit per hour, reaching a maximum of 100°F (37.7°C) on Sunday.
Containment and Stabilization
- Crews set up containment barriers using sandbags to prevent any potential chemical spill from reaching storm drains, creeks, or the ocean.
- An emergency response team successfully drained and neutralized a nearby adjacent tank to reduce the potential for a cascading failure.
The Potential Crack
On Sunday, firefighters observed a potential crack in the tank, which was believed to be relieving internal pressure. This discovery was later confirmed, leading to a decrease in temperature and a reduction in the risk of a catastrophic explosion.
"Letting this thing just fail and blow up is unacceptable to us." — OCFA Division Chief Craig Covey
State of Emergency
California Governor Gavin Newsom declared a state of emergency in Orange County on Saturday, May 23, directing the Governor's Office of Emergency Services and other state agencies to provide support and making state-owned properties available for shelters.
Health and Environmental Risks
Methyl methacrylate is a toxic and flammable substance. Short-term inhalation exposure can cause respiratory irritation, eye and skin irritation, nausea, dizziness, and headaches. Health officials stated that high exposure could lead to severe respiratory distress.
- Air Monitoring: The EPA and OCFA conducted continuous air monitoring. As of Sunday, 24 stationary monitors and drone surveillance had detected no contaminants in the air, and pollution levels within the evacuation zone were reported to be within normal limits.
- Health Complaints: Some residents within the evacuation zone reported symptoms such as sore throat, dizziness, and headaches.
- Environmental Impact: Officials prepared containment measures to prevent any spill from reaching waterways.
Orange County Health Officer Dr. Regina Chinsio-Kwong described the situation as "unprecedented."
Company and Legal Actions
- GKN Aerospace Statement: The company issued an apology for the disruption and stated it was "working around the clock" and cooperating with the OCFA, EPA, and the Occupational Safety and Health Administration (OSHA).
- Regulatory History: The facility received a violation notice following a November 2020 inspection, resulting in a nearly $1 million settlement for failing to maintain records and operating unpermitted equipment.
- Class-Action Lawsuit: A class-action lawsuit was filed against GKN Aerospace by evacuated residents, citing potential impacts on property values.
- Investigation: The Orange County District Attorney opened an investigation and set up an anonymous tipline. U.S. Representative Derek Tran (D-Westminster) also called for a thorough investigation. The cause of the tank overheating remains under investigation.
Current Status and Resolution
On Monday, May 25, officials announced that the threat of a catastrophic boiling liquid expanding vapor explosion (BLEVE) had been eliminated. The evacuation zone was reduced from approximately 50,000 residents to approximately 16,000 residents.
Firefighters removed weather insulation from the tank to improve cooling, and the tank's temperature was confirmed to be decreasing. Officials stated that while the BLEVE threat was gone, the possibility of a smaller explosion, fire, or leak remained.
"This could be a step in the right direction." — OCFA Interim Chief TJ McGovern on the discovery of the potential crack
No injuries were reported throughout the incident.