Garden Grove Chemical Tank Emergency — Methyl Methacrylate Leak Forces Mass Evacuation
An overheating methyl methacrylate tank at a Garden Grove aerospace plant forced about 44,000 people to evacuate a nine-square-mile area of Orange County.
Follow live updates — latest, maps & closures- Location
- Garden Grove, CA
- Occurred
- May 21, 2026, 10:40 PM UTC
- Last verified
- 5h ago
- Sources
- 11 primary sources
Shaded area reflects the affected zone described by cited sources and may be approximate.
A tank of methyl methacrylate (MMA) at a GKN Aerospace facility on Western Avenue in Garden Grove began overheating on May 21, 2026, prompting one of Orange County's largest evacuations in recent memory. According to officials cited by national and local outlets, roughly 44,000 people were ordered to leave a nine-square-mile area as crews worked to keep the tank from leaking or exploding.
What happened
The Orange County Fire Authority was alerted at about 3:40 p.m. on May 21 to a tank containing approximately 7,000 gallons of MMA — within a 34,000-gallon tank — that had begun to overheat. Officials warned the tank could crack and spill, or enter a thermal runaway and explode. Crews have sprayed water to hold the temperature near 90°F; a crack was later found in the tank, and officials have said a low-volume release now appears the most likely outcome. For the latest developments, see the live updates.
Affected area
The evacuation zone is bounded roughly by Ball Road to the north, Trask Avenue to the south, Valley View Street to the west, and Dale Street to the east. It includes parts of Garden Grove, West Anaheim, Buena Park, Cypress, Stanton, and Westminster, including the Little Saigon community. The shaded zone on the map approximates this boundary; confirm your specific status with official sources.
Exposure and health concerns
Officials describe MMA as flammable and volatile, and an irritant to the eyes, skin, and lungs. If you were near the area, follow guidance from the Orange County Fire Authority and the City of Garden Grove, and seek medical attention for any symptoms. For general background, see our chemical spills overview.
What to do now
Follow official evacuation orders. If you have been affected, consider documenting your exposure and keeping records of any costs or medical visits. To check whether your area is within the tracked zone, use the area-lookup tool. More local context is on the Garden Grove region hub.
Answers & guidance
Plain-language, sourced answers to the questions people are asking about this incident.
- How wide is the zone?Garden Grove Blast Radius and Evacuation Zone: What the Map Shows
- Am I in danger?Is the Air Safe to Breathe Near the Garden Grove Chemical Incident?
- Was I exposed?What Is Methyl Methacrylate (MMA)? Hazards and Exposure Symptoms
- Will I get sick?Garden Grove Chemical Exposure: Symptoms and When to See a Doctor
- What should I do?Garden Grove Evacuation: When Can Residents Return Home?
- What should I do?How to Document Exposure and Losses After the Garden Grove Incident
- Who pays for this?Garden Grove Evacuation: Hotel, Food, and Cost Assistance
- Am I in danger?Garden Grove Incident: Schools, Children, and the Evacuation Zone
- Do I qualify for help?Compensation After the Garden Grove Chemical Incident: Your Options
- What happens next?Garden Grove Incident: When Will the Area Be Safe? Cleanup and Testing
Timeline
The Orange County Fire Authority is alerted to an overheating methyl methacrylate (MMA) tank at a GKN Aerospace facility on Western Avenue in Garden Grove.
Initial evacuation orders are issued and then lifted that evening.
Evacuation orders are reissued and expanded to roughly 40,000+ people across a nine-square-mile area; several Garden Grove Unified School District campuses close.
Governor Gavin Newsom declares a state of emergency for Orange County.
Crews stabilize the tank's temperature at about 90°F using sprinklers and unmanned water units, after an overnight rise from about 77°F; readings are taken every 10 minutes.
A drone mission finds a crack in the tank; the interim fire chief calls it a "step in the right direction," and the EPA administrator says a low-volume release now appears most likely.
Common questions
Which areas are under evacuation?
Officials defined an evacuation zone bounded roughly by Ball Road to the north, Trask Avenue to the south, Valley View Street to the west, and Dale Street to the east, covering parts of Garden Grove, West Anaheim, Buena Park, Cypress, Stanton, and Westminster. Confirm your status with the City of Garden Grove and the Orange County Fire Authority.
What is methyl methacrylate (MMA)?
MMA is a flammable, volatile chemical used to make plastics and resins. According to officials, it can irritate the eyes, skin, and lungs. Follow official guidance and seek medical attention for symptoms.
Where can I get official updates?
The City of Garden Grove and the Orange County Fire Authority are posting updates. Air quality is monitored by the South Coast AQMD and EPA AirNow.