Sunday evening, Engines 42 and 12 were alerted for a cart return on fire in the parking lot of Giant Eagle. While enroute, the assignment was upgraded to a structural assignment because the fire was against the structure. The two engines arrived to find a plastic shelter against the building, well involved in fire. The fire was quickly knocked down, and Truck 5’s crew checked the interior of the structure to confirm no extension. The assignment was scaled back to the two engines and the county fire marshal was called to investigate.