@1442 hrs company 10 & 11 were dispatched to Rt 12 EB between Rt 61 and N 5th St Highway for a report of multiple brush fires along the side of the road. Chief 10, Brush 10 & Engine 10-1 responded immediately after dispatched. Chief 10 arrived on location @1445 took command and confirmed the report of several brush fires. Brush 10 entered from the EB exit ramp to N 5th St and was advised to knock down the fire between the railroad bridge and the N 5th St overpass. E10-1 was directed to the Rt 12 on ramp from Rt 61 for a fire on the other side of the railroad bridge. E11 was advised by command to continue up Rt 12 EB to the Spring Valley Rd exit to check for anymore brush fires. With all fires extinguished and no other fires found. both company 10 & 11 were cleared from the incident @1508. It was determined that the fires were started by a vehicle that was producing sparks from it’s rear end. Thank You Co 11. for your assistance!