The washed away section is near Panorama Point in the San Bernardino Mountains and is the main road many use to drive to Crestline and Lake Arrowhead.
According to Caltrans, Route 18 will be closed in both directions from 40th Street in San Bernardino to State Route 189 in Crestline until further notice.
Crews have already started repairs which are expected to take at least a few days, if not weeks. The Press-Enterprise is reporting that repairs will cost over $4 Million.