Potential crack on California chemical tank may ease pressure as crews race to prevent explosion

LA PALMA, Calif. — Southern California officials on Monday said the risk of a devastating vapor explosion has been avoided in an incident involving a storage tank containing methyl methacrylate, a toxic chemical used to manufacture resins and plastics.

A crack in the tank has released pressure and the internal temperature is decreasing, the Orange County Fire Authority said Monday, circumventing the worst-case scenario.

The tank started to heat up and bulge last week, prompting concerns that it would rupture and the chemical inside would explode or leak.

“We are happy to report that the threat of a BLEVE is now off the table. That threat has been eliminated,” interim Orange County Fire Chief TJ McGovern said in an update posted on X, using acronyms to refer to boiling liquid expanding vapor explosion.

The incident has prompted evacuation orders for tens of thousands of people, many of whom are staying in shelters. The orders remain in place as of Monday morning, officials said.

Division Chief Craig Covey, the Orange County fire incident commander, said the temperature inside the tank has dropped from 100 degrees Fahrenheit to 93 degrees.

The crack was identified Saturday night during a visual inspection of the 7,000-gallon tank at the GKN Aerospace facility in Garden Grove.

Garden Grove is in northern Orange County, about 35 miles southeast of Los Angeles and 4 miles from Disneyland in Anaheim.

McGovern said Sunday that crews would conduct an “all-night mission” to determine whether the crack had released pressure from the tank.

Even if the risk of a boiling liquid expanding vapor explosion was averted, he said, “there’s still a potential for explosion.” However, avoiding such an explosion means the evacuation zone can be smaller and crews can focus on cooling the tank, he added.

McGovern said Sunday that air monitoring has shown the possible fissure has not led to the release of toxic air.

A White House official said Monday that the Trump administration “is engaged and monitoring the situation.”

The Environmental Protection Agency has enabled air monitoring at 20 locations around the area, the official said. The Federal Emergency Management Agency has deployed a local officer to coordinate with officials, sent a team to the State Emergency Operation Center and activated its Interagency Modeling and Atmospheric Assessment Center, which models airborne hazards.

Earlier Monday, authorities said that one of three tanks at the facility had been neutralized by introducing a compound into it, but that the other two — including the affected tank — have not.

The authority quashed reports that there may be more than one crack on the tank. “There is also peeling of the weather stripping on the exterior, but this is not an additional crack. There is currently no active leak, and continuous live atmospheric monitoring confirms there are no chemicals leaking,” it said in a post on X.

A spokesperson for GKN Aerospace said Sunday that the company was monitoring the condition of the “affected material” and that crews were working “around the clock to mitigate the risk of a leak.”

Covey told NBC News that an explosion could set off a blast in a nearby 15,000-gallon tank and a 4,500-gallon tank that also holds methyl methacrylate.

Officials said the blast radius, which stretches up to half a mile, would cause severe structural damage and most likely disperse toxic vapors into the air.

Officials also expressed concern that the tank could rupture and release toxic material into waterways.

“We’re talking about possibly one of the worst chemical incidents in California history,” Covey said.

Shelters in Orange County have filled up with frantic locals as 50,000 people are under evacuation orders.

Lydia Green, who lives in Anaheim, about a mile from the facility, is one of them.

“I’m feeling nervous, scared, devastated,” Green told NBC News on Sunday at a shelter at John F. Kennedy High School in nearby La Palma. “I’ve been without my medication, my basic needs — food, hotels, we haven’t had a hotel. It’s been very hard.”

She and her partner, Eugene Smith, had been sleeping in their car. Smith described the ordeal as “like living in a nightmare,” and said he feared a devastating explosion and its aftermath.

“Blowing up and then contaminating everything. Everything. That’s where we live at. That’s our home,” he said.

Jaden Gebelein was also at the shelter and said he was nervous, as he lives on the border of the evacuation zone.

“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. “You hope that it gets managed well and then the worst-case scenario doesn’t happen, because those are people’s houses, and it’s probably going to affect a lot bigger of a radius than they let on.”

The American Red Cross said Sunday that six shelters scattered around the region for evacuees are nearing or at capacity for overnight stays.

Concerns about the 7,000-gallon tank first arose Thursday when Orange County fire officials reported a “vapor release” at the aerospace facility. Further investigation found that the tank’s temperatures were rising.

Firefighters have been using sprinklers and hose lines to cool the tank. McGovern said that during a team operation Saturday night, crews saw that the pin on the temperature gauge was reading 100 degrees Fahrenheit, the highest level it shows, indicating that actual temperatures in the tank could be higher.

Gov. Gavin Newsom declared a state of emergency in Orange County on Saturday. On Sunday, he requested that President Donald Trump issue an emergency declaration to support response operations in the county.

McGovern said officials are working collaboratively and using “outside-the-box thinking” to develop a solution and get families back into their homes.

“We have to get them back,” he said, “but I will assure you we will not get them back until it’s safe to do so.”

Steve Patterson and Shanshan Dong reported from La Palma, Marlene Lenthang from Los Angeles, and Aria Bendix from New York.