Crews are using construction equipment and drones to search the rubble of a Pennsylvania nursing home after a powerful explosion killed at least two people. The blast happened Tuesday at the Bristol Health & Rehab Center, northeast of Philadelphia. Emergency responders evacuated residents amid flames, smoke and even a second explosion. Authorities say a utility crew was responding to reports of a gas odor when the explosion occurred. Investigators are examining whether a gas leak caused the blast. Five people remain unaccounted for, although some may have left with family. The nursing home had been cited for multiple violations in October.