Crack found in California toxic chemical tank could relieve pressure, 40,000 people evacuated

Authorities in California on Sunday said they discovered a crack in a damaged tank of toxic chemicals, potentially relieving pressure as the threat of an explosion has forced tens of thousands of residents to evacuate.

About 40,000 residents were ordered to leave their homes in the Garden Grove area of Orange County, southeast of Los Angeles, on Friday after the tank began to leak, sending fumes over a heavily populated area about five miles from Disneyland.

On Saturday night, firefighters approached the tank to gather information and saw a "potential crack in the tank, which could potentially be relieving some of the pressure in there," TJ McGovern, interim fire chief for the Orange County Fire Authority, said in a video post on X.

"This operation that we did gave us positive intel to make educated decisions today in the positive light," he said, adding that experts are carefully studying the information collected. "We're not there yet, but this was a step in a right direction."

There was no indication as to what caused the leak, which was initially reported on Thursday, and McGovern did not comment on whether the crack was linked to the leak.

The tank contains 7,000 gallons (26,000 liters) of methyl methacrylate, a volatile and flammable liquid used to make plastics.

Firefighters had warned Saturday that the tank was heating up, adding to fears of a catastrophic blast, and have been spraying water to cool the tank.

Orange County Health Officer Regina Chinsio-Kwong said Friday the large exclusion zone around the tank was a necessary precaution.

As of Sunday, evacuees were still not allowed to return home, and shelters had been opened to accommodate them. Disneyland officials said the "resort remains open to guests," and they were keeping a close tab on the matter. 

The US Environmental Protection Agency says methyl methacrylate is irritating to the skin, eyes, and mucous membranes in humans. It can also cause respiratory and neurological reactions in cases of acute or prolonged exposure.

Responders were working to put containment barriers in place to prevent any spilled material from reaching storm drains or river channels that funnel into the ocean.