Thousands ordered to evacuate because of a chemical tank leak in California

(AFP) Tens of thousands of people received evacuation orders in California Friday following a leak of toxic gases from a giant chemical tank that could explode in a densely populated area.

The tank contains 26,000 liters of methyl methacrylate, a flammable and volatile liquid used to make plastic.

"There are literally only two options," said the fire commander in charge of the incident, Craig Covey.

"The tank ruptures and spills a total of 6,000 and 7,000 gallons of very bad chemicals into a parking lot in that area, or two, the tank goes into a thermal chain reaction and explodes, which also affects nearby tanks containing fuel or chemicals," he explained.

"We are arranging these evacuations to prepare for these two options: if it fails or if it explodes," he added.

The emergency is occurring in Garden Grove, in Orange County, southeast of Los Angeles.

Garden Grove Police Chief Amir El-Farra said about 40,000 people received evacuation orders, but tens of thousands are refusing to leave their homes.

County health officer Regina Chinshio Kwong insisted on the need for a wide exclusion zone around the tank.

"If it explodes and there is steam, they will be safe as long as they are outside the area that has been determined as an evacuation zone," she said.

No injuries have been reported so far, and there is no immediate indication of what caused the leak, which was initially reported on Thursday.

Aerial images broadcast by local broadcasters showed emergency services spraying the tank with water hoses in an attempt to cool it and prevent an explosion.

Covey said crews were preparing for a chemical spill, which he described as a "best-case scenario," and preferable to a detonation and a toxic cloud.

Authorities are working to place containment booms to prevent any spilled material from reaching storm drains or river channels that lead to the ocean.