Authorities say a fast-moving grass fire ignited a fire inside the interior of two cement plant structures in Southern California, causing about $500,000 in damage.

Redlands fire Battalion Chief Jim Topoleski said the fire started Sunday at the Cemex plant and wiped out the inside of the buildings.

The San Bernardino Sun reports that about 80 firefighters from multiple agencies battled the fire.

The cause of the grass fire was under investigation.