Crews from Kern County are helping firefighters battle a fast-moving wildfire near expensive properties along the Pacific Coast Highway in Malibu while hundreds of residents fled another fire farther north as forecasters warned of the potential for “extreme and life-threatening” blazes. Los Angeles County Fire crews on Wednesday scrambled to contain the Broad Fire near Malibu’s Broad Beach as authorities shut down the famous seaside roadway. Two structures burned. Northwest of Los Angeles, the Mountain Fire prompted evacuation orders for several communities in an agricultural area near Santa Paula in southern Ventura County. Kern crews are on that scene.