A crack inside a malfunctioning chemical tank at a Garden Grove aerospace plant is indeed reducing pressure inside the container, crews have confirmed, leading fire officials to say they have avoided the most catastrophic threat — a massive explosion.
Data collected from an “all-night mission” by fire crews determined that the threat of a highly destructive blast known as a “boiling liquid expanding vapor explosion,” or “BLEVE,” has been eliminated, interim Orange County Fire Authority Chief TJ McGovern announced in a Monday morning video update.
“The crack is there,” Division Chief Craig Covey added. “We had identified it is there, and the tank has released its pressure.”
Also see: What a crack in the tank means, and why liquid nitrogen is a bad idea
After days of often dire warnings by fire officials and experts, the announcement was the most optimistic update yet by those working to head off a potential disaster. A boiling liquid expanding vapor explosion, which would have likely caused massive damage and released a toxic chemical plume into the air, occurs when a sealed, pressurized container holding a liquid chemical ruptures.
“The threat of a BLEVE is off the table,” McGovern said. “That threat has been eliminated.”
The crisis is not fully averted, authorities cautioned. The possibility of a lesser explosion or a leak remains, and large-scale evacuations are still in place. But the worst possible outcome is not expected to occur.
The temperature inside the tank has also gone down, from at least 100 degrees to 93 degrees, the chief said. That is a key metric: At a high enough temperature, the chemical process was at risk of accelerating out of control, which could lead to a massive explosion. A smaller explosion or a leak from the crack, which is at the top of the tank, remain potential threats.
Also see: How OC evacuees can get assistance during the chemical threat
Addressing concerns from some in the community about the lack of regular updates on that internal tank temperature, Covey said authorities had been allowing the tank to “settle” during the warmer hours and sending crews in to check on it during the cooler overnight hours. Another check was slated to occur Monday evening.
“We were not doing tank temperature checks during the day when the sun was on it in the most extreme conditions for that tank to go in the wrong direction,” Covey said. “We were only doing tank temperature checks at night.”
Danger has not passed
That means that the worst-case scenario of mass damage to nearby homes and businesses, starkly illustrated in “blast zone” maps OCFA released days ago, is no longer one of the likely outcomes.
But it doesn’t mean the danger has fully passed.
Also see: How worried should you be about the chemical spill or explosion’s impact on your health?
A smaller explosion would still release chemicals and send debris from the plant flying, or a leak could release the chemicals from the tank. In either case, wind could disperse a chemical plume farther into the community.
With the dropping temperature and lowering pressure inside the tank, it is now more likely to leak than to explode, according to a Federal Emergency Management Agency brief.
That means the evacuation of roughly 50,000 residents in Garden Grove and nearby communities continues. Those evacuations have lasted for four days, through the holiday weekend.
“We want to be clear that the evacuation zones are still in play,” McGovern said.
Also see: Map shows Garden Grove chemical emergency and evacuation area
At some point, when the threat of any explosion or leak is eliminated, the evacuation zones will be strategically reassessed, the chief said in a Monday morning interview following the video update. But there isn’t a time frame yet for when that will occur.
“When the evacuation zone decreases,” McGovern said, “repopulation occurs.”
Orange County Fire Authority Interim Fire Chief T.J. McGovern answers questions from the media on day four of an ongoing hazmat incident taking place at GKN Aerospace in Garden Grove, conveying that the threat of a bleve, or a boiling liquid expanding vapor explosion, had all but been eliminated, but that dangers remained, from the Incident Command Post at the Los Alamitos Race Track on Monday, May 25, 2026. (Photo by Jeff Antenore, Orange County Register/SCNG)
Evacuee Kimberly Casares sits on a cot with her family at the Elks Lodge in Garden Grove on Sunday, May 24, 2026. Casares lives in the neighborhood behind a pressurized tank filled with methyl methacrylate that started leaking at GKN Aerospace started leaking on Thursday in Garden Grove causing large scale evacuations in Stanton and parts of Garden Grove, Cypress and Anaheim. (Photo by Jeff Gritchen, Orange County Register/SCNG)
Guillermo Chauca of Stanton holds his one-month-old kitten, Copeto, as he and his family hang out outside a temporary American Red Cross shelter at Los Alamitos High School on Monday, May 25, 2026 as they await word on when they can return to the home, which they were evacuated from due to an ongoing hazmat incident at GKN Aerospace in Garden Grove. (Photo by Jeff Antenore, Orange County Register/SCNG)
An American Red Cross volunteer checks on the Chauca family, who were evacuated from their home in Stanton, as they sit together at a table outside a temporary American Red Cross shelter in the gymnasium at Los Alamitos High School on Monday, May 25, 2026. (Photo by Jeff Antenore, Orange County Register/SCNG)
Evacuees Frances Rodriguez holds on to her cat, Rajah at the Elks Lodge in Garden Grove on Sunday, May 24, 2026. The pair, along with her husband, Paul Rodriguez, are staying in a tent at the lodge. A pressurized tank filled with methyl methacrylate started leaking at GKN Aerospace started leaking on Thursday in Garden Grove causing large scale evacuations in Stanton and parts of Garden Grove, Cypress and Anaheim. (Photo by Jeff Gritchen, Orange County Register/SCNG)
Quoc Ngo feeds his 4-year-old daughter, Annie, at Golden West College’s Red Cross Shelter in Huntington Beach on Sunday, May 24, 2026. Meals are being provided by World Central Kitchen for families like Ngo’s who have been displaced by the potential chemical disaster at the GKN Aerospace facility in nearby Garden Grove. The family could not find an available shelter the first night of the evacuation and had to sleep in their car. They were finally able to secure spots at the college yesterday evening, along with their Stanton neighbors.(Photo by Mindy Schauer, Orange County Register/SCNG)
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Orange County Fire Authority Interim Fire Chief T.J. McGovern answers questions from the media on day four of an ongoing hazmat incident taking place at GKN Aerospace in Garden Grove, conveying that the threat of a bleve, or a boiling liquid expanding vapor explosion, had all but been eliminated, but that dangers remained, from the Incident Command Post at the Los Alamitos Race Track on Monday, May 25, 2026. (Photo by Jeff Antenore, Orange County Register/SCNG)
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Crafting a solution
When they first arrived at GKN Aerospace on Western Avenue on Thursday, fire crews were told by a project manager there was nothing they could do: A tank filled with 7,000 gallons of methyl methacrylate, a flammable, toxic and highly volatile chemical, was going to fail, either spilling and sending the chemicals pouring into a parking lot or exploding with a fireball that would send a plume of chemicals into the wind.
Also see: What is methyl methacrylate?
“For a first responder to hear that there’s no options is unacceptable,” McGovern said in the interview. “We knew we had to come up with options, solutions. That’s what we do.”
While fire officials publicly warned of the likelihood of an explosion or leak, they also began troubleshooting with a group of experts, including specialists with ties to Los Angeles, San Bernardino and Long Beach.
Gummed up valves and concerns that drilling into the tank may spark a reaction with the volatile chemicals seemed to rule out obvious solutions. But a continued water deluge of the tank appeared to keep an explosion or leak at bay, giving the experts time to craft potential out-of-the-box solutions.
“We developed a think tank,” McGovern said. “These gentlemen got into a room and started developing options. That was a success. These are unprecedented issues.”
The current goal is to keep lowering the temperature of the tank to 50 to 60 degrees to stabilize the situation and put some of those solutions the experts have been crafting into play.
Crews and chemical experts, at their own personal risk, have carried out the overnight operations to get a first-hand assessment of the compromised tank. That led to the discovery — overnight on Saturday — of the crack at the top of the tank.
Also see: Why experts haven’t been able to find a solution the chemical threat
They don’t know if it is a new crack or one that previously existed. Since it is at the top of the tank, the crack has not yet resulted in any chemicals leaking.
The crews went back in Sunday night, McGovern said, and confirmed the crack was releasing pressure.
Then, the chief said, they began removing some of the outside skin of the tank and the insulation around it. Those layers were keeping the temperature inside the tank high, despite the cooling water crews were spraying it down with.
Once the water was directly hitting the tank, the temperature started to fall.
“What we found was the internal temperature started dropping,” McGovern said.
The chemical also appears to be solidifying, McGovern said. But that process seems to be happening from the outside in, so the current density of the center is unclear.
“We need to see the density inside,” the chief said. “It solidifies into a plastic form. We don’t know yet if all the substance has solidified.
“That’s what we believe is going on. That’s what the readings are showing,” he added. “At the end of the day — and I don’t mean today, but at the end of the day — if we open that tank up, (there’s) a big chance that it’s a big plastic pill.”
No leaks so far
Air quality experts who have been tracking the atmosphere near the tank have not detected any contaminants so far. But the chief said that has made it challenging at times to impress upon people the reason for the evacuations. Unlike the smoke and flames of a wildfire, the danger of a failing chemical tank isn’t as obvious to the naked eye.
“There’s nothing in the air,” the chief said.
Even with the internal temperature of the tank appearing to be trending down, authorities said, it is still too risky to send crews in during the day. So they will again wait until Monday night to directly approach the tank.
In the event of a new crack that would allow chemicals to leak out, crews have set up a system of sand barriers to divert the flow and prevent the chemicals from entering storm drains or river channels.
In an “earliest, best case scenario,” changes to the evacuation orders still wouldn’t come until at least Tuesday, if not later, OCFA Capt. Nick Garton said.
A holiday away from home
For those forced out of their homes since Friday, Memorial Day was yet another uncertain day in a long-running evacuation.
Jacqueline Riegos, a 51-year-old Stanton resident, and her service dog, Jericho, were planning to spend the night at Kennedy High School. Riegos lives a little more than 2 miles from the GKN site, and she got a phone alert Thursday evening.
They evacuated, then were told they could go home — before being reevacuated Friday morning.
“A lot of us left with just what we had on,” she said.
Riegos has been sleeping in her car since then, but on Monday, she became worried about her dog getting heat stroke. She also struggled herself. She’s had three back surgeries and is recovering from a hip replacement, Riegos said. Initially, she avoided the shelters because she was worried they’d separate her from her dog, a rescue who is anxious.
Stella Nunez, 53, left her Anaheim apartment Thursday night with her dog, Reagan Messi. She stayed with her daughter Saturday night, but her daughter’s place is small, so she and Reagan spent last night at the Elks Lodge, which opened their doors to evacuees this weekend.
It’s been a hard and emotional week, Nunez said. She just got out of the hospital after a bout of anemia on Wednesday and was evacuated two days later.
But “they’re all angels,” she said of the Elks Lodge workers. Before today, she hadn’t laughed or smiled since Friday.
“Today, I smiled,” Nunez added.
Jackie Page, club manager of the Elks Lodge, said that while their facility is not an official evacuation shelter, they opened their doors this weekend for those with nowhere else to go. They were offering open RV spots, space for tents in their park and ballroom space for sleeping bags.
“We’re humans,” she said of the Elks lodge community. “We have the space. We have the capacity.”
Janet and Alyana, a mother and daughter who preferred to be identified by only their first names, evacuated from Stanton on Friday night. Both appeared bleary-eyed and weary on Monday, sitting on picnic tables outside the Kennedy High School shelter, where they ended up after sleeping in their car for two nights when other facilities they visited were full.
Most of the shelters that opened in the wake of the evacuations, in fact, remained at capacity early Monday, with authorities indicating that only a new Los Alamitos High School shelter and Golden West College were not full.
“It is what it is,” Janet said. “We’re alive.”
State of emergency
Gov. Gavin Newsom, meanwhile, declared a state of emergency on Saturday afternoon, opening the way for extra resources.
The White House, on the request of Newsom and other California leaders, also approved a federal emergency declaration to aid with the ongoing response at the aerospace company. That would include federal cost-sharing for a response that has already run up a hefty price tag not only for the efforts to address the compromised tank but also to evacuate and shelter so many people.
The White House, in a statement released Monday morning, said the administration is “engaged and monitoring the situation in Garden Grove.”
“The U.S. EPA has integrated with the local Unified Command composed of state and local agencies, and has enabled air monitoring at 20 locations around the area,” the White House said. “FEMA has deployed a Liaison Officer to coordinate with officials and has also deployed a team to the State Emergency Operation Center to support incident contingency planning. FEMA has also activated the Interagency Modeling and Atmospheric Assessment Center to provide plume modeling of airborne hazards, informing incident leadership and contingency planning.”
While bringing the crisis to a close has been the main focus, the owners of GKN Aerospace have already come under heavy criticism for the apparent failure of any emergency systems involving the chemical tank.
The United Kingdom company, a worldwide leading manufacturer of cockpit windows, jet canopies and aviation widows for civil and military aircraft, has been operating in Garden Grove for decades and employs more than 500 local workers. It previously paid a nearly $1 million fine to settle numerous environmental violations. The company on Sunday released an apology in the midst of the chemical incident.
Orange County District Attorney Todd Spitzer has already announced his office is investigating the current failure of the chemical tank. Prosecutors on Sunday sent a letter to GKN Aerospace ordering the company not to destroy any documents or records pertaining to the business. They warned that destroying evidence in the midst of an active investigation would lead to criminal charges.
Spitzer has opened a hotline for receiving tips on the chemical tank crisis at 714-347-8714. Anyone with information can also email prosecutors at tipster@ocdistrictattorney.gov.
And at least half a dozen law firms also pledged to file lawsuits seeking class-action status on behalf of residents and businesses impacted by the evacuations.
Staff writers Tony Saavedra and Kaitlyn Schallhorn contributed to this report.