An unoccupied school bus and three other vehicles were involved in a major accident this morning in Upper Township. The Upper Township Rescue Squad reports that the squad and Seaville Volunteer Fire Department both responded to a four vehicle accident on Route 50 near Tyler Road in the Greenfield section of the township. Six patients were evaluated at the scene; only one went to a trauma center for evaluation. The school bus was parked and unoccupied at the time of the accident. New Jersey State Police are investigating.