CASTAIC, Calif. — Firefighters fought to maintain the upper hand on a huge and rapidly moving wildfire that swept through rugged mountains north of Los Angeles and resulted in more than 50,000 people being put under evacuation orders or warnings.

The fire threat remains critical in Southern California, where thousands of residents were under evacuation orders Wednesday as fire crews battled the out-of-control Hughes Fire near Castaic, a suburb in the foothills and mountains of northern Los Angeles County.