Box 1-4 sent "B" platoon companies to 541 S. 19th Street near Brookwood for a structure fire around 2045 hours. Reports indicated fire through the roof. Units arrived on location with fire showing from the B side of an occupied, 3 story, duplex. All occupants were reported to be out of the building. Battalion Chief 4 (Hartman) arrived on location and requested the first alarm assignment. Members quickly stretched multiple lines while Tower 1 prepared to go in service to perform ventilation. The fire was knocked down quickly knocked down as heavy smoke poured from the upper floors of the dwelling. Extensive overhaul including the use of foam was needed to fully extinguish the fire. Box alarm: Wagon 4, Squad 8, Towers 1, 3, Chief 4; 1st alarm: Wagon 3, Tower 2, York Rescue 69, and Air 13 (West Shore).