Authorities in Southern California said a damaged chemical tank that cracked over the weekend may be releasing pressure, reducing the risk of a catastrophic explosion, as roughly 50,000 residents remained under evacuation orders Sunday.
Officials have been racing for days to stabilize a tank containing methyl methacrylate at the GKN Aerospace Transparency Systems facility in Garden Grove, about 40 miles south of downtown Los Angeles. The chemical is used in the production of plastics and resins.
Orange County Fire Authority Interim Chief TJ McGovern said crews planned an “all-night mission” Sunday to determine whether pressure inside the tank had been relieved.
“We are not there yet,” McGovern said in a video update posted to social media, urging residents to remain outside the evacuation zone while emergency operations continued, per the Associated Press.
Officials said the tank overheated Thursday and began venting vapors, raising fears of a boiling liquid expanding vapor explosion, or BLEVE, which authorities described as a worst-case scenario capable of causing widespread destruction and dispersing toxic chemicals.
McGovern said a visual inspection Saturday night identified what appeared to be a crack in the 7,000-gallon tank. If the fissure is releasing pressure, officials believe it could significantly reduce the likelihood of a catastrophic blast.
“With this new information, it could change our trajectory and our strategy to this event,” McGovern said, per NBC News.
In a later statement, the fire authority said there was only one known crack on the tank, disputing online rumors that multiple cracks had formed. Officials also said continuous air monitoring had not detected any active chemical leaks.
Firefighters have repeatedly sprayed water onto the tank to cool the chemical inside. State Sen. Tom Umberg said Sunday that the tank’s internal temperature had reached 100 degrees Fahrenheit, up 10 degrees from the previous day.
Authorities said drones were monitoring temperatures every 10 minutes for sudden increases. Crews also installed containment barriers to prevent chemicals from reaching storm drains, nearby creeks, or the ocean in the event of a leak.
Craig Covey, an Orange County fire division chief overseeing the incident, warned that an explosion could trigger explosions in two nearby tanks that also contain methyl methacrylate.
“We’re talking about possibly one of the worst chemical incidents in California history,” Covey said, NBC News reported.
Gov. Gavin Newsom declared a state of emergency Saturday and requested federal assistance from President Donald Trump to support response efforts.
No injuries have been reported.
Garden Grove residents displaced by the evacuation continued filling shelters across Orange County. Some evacuees slept in cars or on mats at temporary shelters, including one at a high school in nearby La Palma.
“I’m feeling nervous, scared, devastated,” resident Lydia Green told NBC News while staying at a shelter on Sunday. “I’ve been without my medication, my basic needs — food, hotels, we haven’t had a hotel. It’s been very hard.”
Her partner, Eugene Smith, described the ordeal as “like living in a nightmare.”
“Blowing up and then contaminating everything. Everything. That’s where we live at. That’s our home,” Smith said, per NBC.
Another evacuee, Jaden Gebeleinis, questioned why industrial facilities were located so close to residential neighborhoods.
“It’s a lot of anger. … I feel like why there are these facilities right next to a bunch of houses? And it makes me upset, too,” he said, according to NBC.
Officials said the evacuation zone could shrink if crews confirm the tank is no longer at risk of a BLEVE. Until then, authorities said residents will not be allowed to return home.
“We have to get them back,” McGovern said, per NBC, “but I will assure you we will not get them back until it’s safe to do so.”
Health officials warned that exposure to methyl methacrylate can cause respiratory problems and irritation to the eyes, skin, and throat. Authorities noted, however, that the chemical has a strong odor and may be detectable even at levels not considered harmful.
Meanwhile, some residents have already filed a federal class-action lawsuit against GKN Aerospace Transparency Systems, arguing the incident could permanently affect surrounding property values.
The company said it was “working around the clock to mitigate the risk of a leak” and apologized to residents and businesses impacted by the evacuation orders, according to AP.
State records show that GKN Aerospace agreed in 2025 to pay more than $900,000 to settle alleged violations involving emissions, permitting, and recordkeeping.
