At 1720 hours, Box 1-5 sent Wagon 3, Engine 1, and Truck 32 to Cameron and Hanna Streets for a structure fire. PD quickly reported a column of black smoke. Incoming companies also reported a heavy smoke column prompting Captain 4 (Wise) to issue a first alarm assignment. Wagon 4 and Tower 1, which just cleared an elevator rescue downtown, arrived on side B with a well involved, one-story commercial building with explosions. A second alarm was struck bringing in county mutual aid companies from the East and West Shore to the scene. All companies operated defensively using the heaviest water lines. Multiple five inch supply lines were laid from various intersections along busy Cameron Street during rush hour and shutting down a major artery for traffic in the city. Master streams from Tower 1 (Harrisburg), Truck 34 (Paxtonia), Truck 32 (Progress), Truck 12 (Lower Allen) along with numerous hand lines and ground appliances poured water on the stubborn fire for hours that at times blanketed the scene with heavy, ground level smoke. Command requested a third alarm that brought additional mutual aid to the scene and for coverage at City Stations 1 and 2. The fire building was a long, one-story, warehouse type building that housed a complex of businesses. The fire originated in an auto salvage operation and damaged at least 3 other businesses in the complex. A firewall kept the fire from extending east towards side A of the warehouse. The rear portion of the building collapsed creating pockets of fire that smoldered well into the night. The fire was placed under control around 2100 hours.