Officials say at least 300 firefighters are battling a 400-acre fire in San Luis Obispo County near Shell Beach and Pismo.

According to the California Department of Forestry and Fire Protection (CAL FIRE), the blaze is now 50 percent contained.

It has burned at least one home and several trees. CAL FIRE says the structure threat has been mitigated but fire activity continues to burn within the perimeter.

Roads have now reopened in Pismo.

CAL FIRE says they expect to have full containment by late Wednesday afternoon.

The cause of the fire is under investigation.