Toxic chemical leak forces evacuation of over 44,000 near Los Angeles

More than 44,000 residents have been evacuated in Garden Grove, California, after a tank containing 34,000 gallons (128,704 liters) of methyl methacrylate began leaking at an aerospace manufacturing facility, the Orange County Fire Authority (OCFA) said Friday.

The leak was reported Thursday, May 21, 2026, at the facility located 40 miles (64.4 kilometers) southeast of Los Angeles. The tank contains methyl methacrylate, a toxic and highly flammable chemical used in the manufacture of acrylic plastics. Authorities said the tank system failed after the chemical overheated, causing the tank to start leaking vapors into the air.

OCFA Division Chief Craig Covey told reporters: "It fails or it blows up." He outlined two possible outcomes: the tank fails and spills 6,000 to 7,000 gallons of chemicals into the surrounding parking lot, or the tank goes into thermal runaway and explodes, affecting adjacent tanks. "There are literally two options left," Covey said. The compromised tank is next to two other chemical storage tanks.

"It is a highly toxic substance," OCFA Division Chief Nick Freeman told a news conference. "It's extremely flammable, and in its current state, very reactive, and can cause that explosion."

OCFA officials said air quality readings remained within "healthy limits" as of Friday. Containment barriers have been placed to prevent any spill from entering storm drains, river channels, or reaching the ocean. Officials described a spill as the "best case scenario, believe it or not," compared to an explosion that could produce a toxic plume.

No injuries have been reported as of Friday. The cause of the overheating is under investigation. Evacuation centers have been set up by the OCFA, alongside an information hotline. Officials have asked people to "refrain from calling to offer suggestions" as to how to respond to the incident.