Tens of thousands of residents have been evacuated and Gov. Gavin Newsom has declared an emergency as officials try to thwart an explosion at the facility in the city of Garden Grove.

Authorities in Orange County say they’re unable to control the valves on a tank that contains methyl methacrylate, a chemical used in the manufacture of plexiglass.

An official said there's no active leak, but evacuations orders are to prepare for either a spill or an explosion from a failing chemical tank.

Authorities are racing to prevent the explosion of a leaking storage tank containing hazardous chemicals in Garden Grove, California, prompting evacuations for approximately…