Authorities said the leak began Thursday afternoon at a facility in Garden Grove, a city in Orange County, where an overheated storage tank holding methyl methacrylate -- a flammable chemical used in the production of acrylic plastics -- began venting hazardous vapors, Xinhua reported.

Officials said the facility operated by GKN Aerospace contains three storage tanks in total, with one suffering a cooling system failure. Emergency crews initially believed they had stabilized the situation overnight, but worsening conditions on Friday prompted authorities to expand evacuation orders, forcing school closures and emergency responses across multiple cities.

Residents in Garden Grove and nearby communities were affected by the evacuation directives as emergency crews warned the compromised tank could either rupture and spill thousands of gallons of chemicals or explode.

"This thing is going to fail, and we don't know when," Orange County Fire Authority Chief Craig Covey said during a public briefing.

No injuries or deaths have been reported.