Allentown firefighters battle a fire after an explosion near the intersection of 13th and Allen Streets in Allentown, Pa., early Thursday morning Feb.10, 2011. Several buildings are involved and at least two people are still unaccounted for. About 750 people, including elderly residents of a high rise, were cleared from the area. Many were taken to the Allentown fairgrounds for temporary refuge. (AP Photo/Rich Schultz)