At 0134 hours, Box 88-1 sent Company 88, Engines 54, 59-1, and 74-1 to the area of 20 N. Pine Street for a house on fire. Chief 88 went enroute and advised of multiple calls and possible 3 occupants still inside. The first alarm was requested at 0138 hours bringing Engines 55, 71, Rescue 59, Truck 50, and Air 41. Chief 88 arrived on location with a single story dwelling fire showing side Bravo and the first engine to lay in from Emmaus Street. Despite occupants going back in the structure they were all accounted for as companies arrived on location. As members stretched lines heavy fire broke through the roof and there was a partial collapse on the B/C corner. 2 lines were stretched and operated making a good stop on the fire and preventing the rest of the house from becoming involved. The fire was placed under control in about an hour with extensive overhaul required before companies cleared the scene.