Authorities fear that a pressurized tank containing methyl methacrylate could rupture near residential neighborhoods in Orange County

Up to 50,000 residents have been ordered to evacuate parts of Orange County, California, as authorities warned that a damaged chemical tank remains at risk of leaking or exploding.

California Governor Gavin Newsom has declared a state of emergency in Orange County as emergency crews work to contain the crisis at a GKN Aerospace facility in Garden Grove, about 61 kilometers (38 miles) from Los Angeles. The pressurized tank contains between 6,000 and 7,000 gallons (22,700-26,500 liters) of methyl methacrylate (MMA), a highly flammable industrial chemical used in plastic production.

The incident began Thursday when the tank started venting vapors, according to the Orange County Fire Authority. Officials later said there was no active gas leak or plume but warned that the vessel remained unstable and could still fail.

Responders initially believed the situation had stabilized after crews cooled the exterior with water, following drone thermometer readings showing the temperature had fallen to 61 degrees Fahrenheit (16 degrees Celsius). It was later discovered that the drones had measured only the outer shell of the container, while manual readings showed internal heat levels were still rising.

By Saturday, temperatures inside the vessel had climbed to around 90 degrees Fahrenheit (32 degrees Celsius), with emergency personnel saying the heat was increasing by roughly one degree Fahrenheit per hour. Authorities also said damaged or "gummed up" valves were preventing crews from removing the chemical or relieving pressure.

Emergency teams have tried cooling the vessel and adding a neutralizing agent, while containment barriers have been set up to limit environmental contamination if the tank fails. Orange County Fire Authority Chief Craig Covey described the incident as a "worst-case scenario" and said the threat of a leak or explosion remained possible.

"Letting this thing just fail and blow up is simply unacceptable to us," Covey said.

Evacuation orders were initially limited to residents living within 3 miles (4.8 kilometers) of the site, but were later expanded to parts of six Orange County cities: Garden Grove, Cypress, Stanton, Anaheim, Buena Park, and Westminster, affecting up to 50,000 people.

The substance can ignite easily and release toxic fumes if the container ruptures or explodes. Exposure to MMA may cause respiratory problems, neurological symptoms, skin and eye irritation, and, in some cases, unconsciousness, according to health officials.

(RT.com)