As freezing rain started to impact the local area the motor vehicle assignment was sounded at 3:17 PM for Interstate 81 South Bound at MM 20, a 15 Box (West End Fire and Rescue).  Deputy Chief 15 arrived on the scene to find numerous vehicles involved with multiple patients laying in the roadway and numerous patients trapped in 2 other vehicles.  The mass casualty assignment was established which brought numerous additional EMS resources to the scene.  Squad 7 arrived on the scene and was assigned to a vehicle that had 3 patients trapped.  Engine 7-1 arrived and assisted with extrication.  In total there were 2 Priority 1 patients, 3 Priority 2 patients, 2 Priority 3 patients, and unfortunately 2 Priority 4 patients.  Company 7 units remained on the scene until 4:22 PM.