California crews conducted an overnight operation at the site of a chemical leak in Orange County and said Monday that the threat of an explosion is "off the table."

Southern California officials have expanded an evacuation zone in several Orange County cities over a toxic chemical tank that they say is "actively in crisis."

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.