Tens of Thousands Ordered to Evacuate Over Chemical Tank Explosion Risk in California

A damaged storage tank at an aerospace plastics facility in Orange County, California, was at risk of exploding or leaking on Sunday, potentially releasing some 7,000 gallons of volatile chemicals. 

Around 50,000 people have been ordered to leave their homes in the area while firefighters sprayed the tank with water hoses to cool it down and prevent it from exploding. There is no timeline for when they will be able to return home. Governor Gavin Newsom has also declared a state of emergency for the county.

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The tank, at GKN Aerospace in Garden Grove, contains the chemical methyl methacrylate, used to make plastic. 

Here’s what you need to know about the tank.

Risk of respiratory issues, coughing and wheezing

Authorities first responded to GKN Aerospace, about 40 miles south of downtown Los Angeles, on Thursday 

The problem started when the tank temperature began to rise, causing it to bulge and activate a nearby relief valve and sprinkler. It is not clear yet what caused the temperature to increase. 

The methyl methacrylate inside the tank could irritate people’s eyes and skin, according to the Environmental Protection Agency (EPA), and can lead to respiratory issues like chest tightness, coughing and wheezing.

“There are literally two options left remaining: One, the tank fails and spills a total of about [6,000] to 7,000 gallons of very bad chemicals into the parking lot and that area,” Orange County Fire Authority (OCFA) Incident Commander and Division Chief Craig Covey said in a press conference on Friday. “Or two, the tank goes into a thermal runaway and blows up, affecting the tanks that are around it that have fuel or chemicals in them as well.”

By Sunday morning, though, OCFA Interim Chief TJ McGovern said that emergency crews late Saturday night found a pressure-relieving crack in the tank, putting relief efforts on a “new trajectory”.

“We’re being told that the tank will fail,” EPA Administrator Lee Zeldin told CNN’s Jake Tapper Sunday morning. Zeldin said that an explosion would be the most “catastrophic” result of the leak, but he said the most “likely” result is not an explosion but “a low-volume release, where the local authorities are going to be able to monitor, neutralize, and contain a threat.”

“Right now, this is an emergency response. This isn’t yet an environmental response, and the scale of that environmental response will be determined based off of what happens when that tank fails,” he added.

Lawsuit filed against GKN

GKN Aerospace released a statement apologizing to locals affected by the storage tank incident at its Garden Grove site.

“We continue to monitor the condition of the affected material and are working round the clock to mitigate the risk of a leak,” the company said. “We are acutely aware of the uncertainty this incident is causing and sincerely apologise for the ongoing disruption to the local community.”

By Saturday, though, California-based X-Law Group P.C. and Presidio Law Firm LLC had already filed a lawsuit against the company on behalf of two Garden Grove residents who were told to leave their home on Thursday.

“There is no good outcome here for the people who live nearby,” the lawyers for the residents wrote in a statement. “In the best-case scenario, a slow, controlled leak still forces residents out of their homes for an indefinite period, disrupting families, businesses, and daily life.”

TIME has reached out to GKN Aerospace over the lawsuit.

Orange County District Attorney Todd Spitzer launched a probe into GKN on Saturday, promising to hold the company “accountable.”

“For goodness’ sake, they’re in the middle of a commercial area, residential, it’s an urban population. … It’s irresponsible, it’s horrific, and I’m angry about it,” Spitzer told CBS Los Angeles on Saturday. 

“I am scratching my head, asking a question I think everybody is asking: How in the world could this entity … a multi-million dollar company that’s responsible for this kind of manufacturing using volatile chemicals, not have any redundancy or backup systems for purposes of cooling?”