EWING, N.J. (MyFoxPhilly) – Emergency responders are at the scene of an explosion and fire at a condo complex in Mercer County after a gas line was struck by a contractor, PSE&G now confirms. The location is Crockett Lane in the Heritage Crossing development in Ewing, and the reported explosion occurred around 1 p.m. Tuesday. Several people posted to Twitter that they felt the ground shake around the time the fire broke out. At least 10 ambulances were called to the scene to transport injured persons. Capital Health Regional Medical Center in Trenton reports that it’s treating six patients, one of whom is in critical condition. Five others are being evaluated with head injuries, respiratory problems or broken bones.