Garden Grove city officials discovered a tank containing approximately 26,500 liters of methyl methacrylate (MMA) leaking vapor at a local aerospace manufacturing company on 22/5.

By 23/5, officials updated that there was no longer a gas leak, but stated the tank was in a severely unstable and uncontrollable condition, potentially rupturing or exploding at any moment. MMA is a volatile, flammable industrial chemical often used in acrylic plastic production.

Craig Covey, chief of the Orange County Fire Authority, stated in an update on 23/5: "Currently, there are only two possibilities. One is the tank rupturing, spilling all toxic chemicals onto the parking lot in the area. The second is the tank entering a thermal runaway state and exploding, impacting surrounding tanks which also contain fuel or chemicals."

Officials spray water onto the heating MMA tank in Garden Grove, California, on 22/5. *Photo: AP*

Officials are implementing evacuations for 40,000 residents in the area, based on these two scenarios. The evacuation order extends across 5 other Orange County cities: Cypress, Stanton, Anaheim, Buena Park, and Westminster.

More than 12 schools have temporarily closed, and those located near the affected area have canceled outdoor activities.

Covey stated the facility has three tanks. The unstable MMA tank had heated up and bulged on 22/5. Neutralizing agents were ineffective, and the option to drain the chemical was impossible due to a damaged valve system.

Officials spray water onto the heating MMA tank in Garden Grove, California, on 22/5. *Photo: KABC*

Officials stated it is currently unclear when residents can return home.

"This substance is highly volatile, very toxic, and extremely flammable," Covey said, urging residents to evacuate. "This is not a preventative measure. The incident will occur, unless someone exceptionally brilliant finds a way to control it. This tank will fail; we just don't know when."

Garden Grove has a population of approximately 172,000, including about 73,000 Asian residents. Garden Grove, along with Westminster, serves as one of the two main centers of Little Saigon in Orange County, home to the largest Vietnamese community outside of Vietnam.

By Duc Trung (AP, ABC News, OC Register)