A failed cooling system may have triggered the dangerous chemical leak at a Garden Grove aerospace facility that led officials to evacuate roughly 50,000 residents over an explosion threat, officials said.

Orange County Fire Authority Chief TJ McGovern said that a pressurized storage tank holding 7,000 gallons of methyl methacrylate, a highly flammable liquid used in plastic manufacturing, began heating up after the cooling mechanism stopped working for reasons that have yet to be determined.

“We don’t know why, but it stopped cooling,” McGovern told The Los Angeles Times on Tuesday.

“So that’s what started this event, to where the product heated up… and that’s how this whole response started. We’re just now being able to get to the tanks, so there’s definitely more to come of what caused it.”

The crisis erupted Friday when officials feared one of three chemical tanks at the aerospace facility could explode in blast capable of causing major destruction across the surrounding area.

The threat prompted mass evacuation orders affecting more than 50,000 people.

After further inspections over Memorial Day weekend, crews discovered the tank had developed a crack that lowered internal pressure, easing fears of a massive explosion.

“Yesterday we really turned a corner,” McGovern said.

GKN Aerospace has been identified as the source of the significant chemical discharge.

President Donald Trump on Monday approved a federal emergency declaration after California Gov. Gavin Newsom and state leaders spent days warning the toxic leak in Garden Grove could erupt into a full-blown disaster.

But as panic spread, crooks allegedly seized the opportunity.