At 2:30 a.m. Monday morning Downey FD, LACoFD and Vernon FD responded to Erickson and Descanso st for a reported structure fire. Arriving crews discovered two well involved structures on the property. The structures are a few hundred yards apart. Knockdown was achieved after approximately an hour and 20 minutes. Arson is being investigated as a possible cause of the fire. Downey FD is handling the investigation at this time.