At approx. 0505 hours units were alerted to a report of a tractor trailer accident on route 502. While enroute Communications advised Rescue 98 that a tractor trailer had left Interstate 81 and traveled 100 feet down an embankment. Police advised there was entrapment and a large diesel fuel spill. With the updated information Rescue 112 and Engine 93 were requested. Rescue 98 arrived and found the driver DOA. Units remained on the scene for approx. 2 hours controlling the hazards and assisting PSP.