An emergency responder was killed Tuesday after an ambulance was involved in a crash with an tractor trailer in front of a hospital. The incident occurred in front of Carolinas Medical Center-Union along U.S. 74 in Monroe, just before 11 a.m. Tuesday morning. A tractor trailer truck driven by Wallace Kenneth Murphy, Jr. of Madison, NC was traveling westbound on US 74 when it collided with an ambulance as the ambulance pulled into the roadway, police told WBTV.