Around 0315 hours Box 1-3 sent "A" platoon companies to 688 Schuylkill Street for a structure fire. Responding units were advised that PD was on location with a working fire and the home was possible vacant. Uptown companies Wagon 3 and Tower 2 arrived on location with heavy smoke from the first and second floors of a 2 story duplex. Chief 4 (Horst) requested the balance of the first alarm bringing Wagon 4, Tower 3, and Rescue 69 (RIT) to the scene. While companies were preparing an aggressive interior attack reports of an occupant trapped was reported to command. Chief 4 requested an additional "1 and 1" to the scene with Penbrook Engine 30 and Progress Truck 32 handling that assignment. Companies quickly knocked down a fire involving the first floor of 690 Schuylkill Street which was unoccupied. The primary search proved to be negative. Fire was able to extend to the upper floor of the fire building via walls and void spaces. Crews opened up the roof and continued to pull ceilings to contain the fire in about 30 minutes. The exposure building suffered from smoke and water damage and a family of 5 was displaced from that residence.