Authorities are bracing for the possibility that a damaged chemical tank at a facility in Southern California could leak or explode.

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 Orange County.

A damaged chemical tank in Southern California has a crack, potentially lowering the risk of a cataclysmic explosion, though an evacuation order remains in effect for some 50,000 area residents with ...