40,000 Evacuated in Southern California as Chemical Tank Threatens Leak or Explosion

Firefighters in Garden Grove are working to stabilize the failing tank holding methyl methacrylate while seeking solutions to avert disaster.

Water is sprayed on a tank that overheated at an aerospace plant in Garden Grove, Calif., on May 22, 2026. Jeff Gritchen/The Orange County Register via AP

Roughly 40,000 people in Garden Grove, a Los Angeles suburb, were evacuated on May 22 after a chemical storage tank was determined to be at risk of failing and spilling thousands of gallons of toxic material or exploding.

The malfunctioning tank holds methyl methacrylate, a flammable and volatile chemical used in plastics manufacturing for aerospace applications, igniting widespread worries over potential toxic vapor release.

The situation broke out on May 21, when the tank at a manufacturing facility started displaying signs of instability. By May 22, an update increased fears of an explosion, Orange County Fire Authority interim Chief TJ McGovern said.

Firefighters were working to cool the tanks with a mechanical device operated from a safe distance, stabilizing the temperature and buying critical time, officials said.

“I know I keep talking about we were handed this situation where there’s only two things that can happen: it could crack and leak, or it could blow up. That’s not acceptable to us,” Craig Covey, division chief of the Orange County Fire Authority, said in a video posted on social media.

Covey said in a later video, “I have an entire team actively working locally, regionally, across the state, and across the country, to try to figure out how to fix this.”

He said he is working to “get all these brilliant minds together to put a plan together.”

In an earlier announcement, Covey said the tank could fail and spill up to 7,000 gallons of toxic chemicals or explode and compromise neighboring tanks.

Garden Grove, which is home to 172,000 residents, is located approximately 30 miles south of Los Angeles. The evacuation zone affected neighborhoods in and around the city and extends to nearby areas, including parts of Anaheim, Cypress, Stanton, Buena Park, and Westminster.

Officials established three evacuation shelters in Garden Grove, Anaheim, and Cypress. Schools and roads in the affected areas were closed.

Garden Grove Police Chief Amir El-Farra said approximately 15 percent of those under evacuation orders were refusing to leave.

Health officials said that released vapor could prompt severe respiratory issues with prolonged exposure. Air quality monitors, however, had not detected any vapor as of May 22, said Dr. Regina Chinsio-Kwong of the Orange County Health Care Agency.

“You are safe as long as you are out of the zone that was determined to be an evacuation zone,” Chinsio-Kwong said.

Methyl methacrylate has a sharp, fruity odor. Some residents miles away reported smelling it amid the unfolding events.

Reuters contributed to this report.