At dinner time this evening, the township companies responded to I81 NB MM55.7 for an accident. C33 was advised of confinement. Company 33 encountered stand still traffic from MM53 and requested Squad 31 not pass the crossover at MM56.4 and confirmed if traffic was stopped to proceed south in the NB Lanes. Chief 131 arrived first and confirmed traffic was stopped. Squad 31 crew removed the drivers door for extrication. After splitting traffic for several miles, Co. 33 and both Ambulances arrived on scene with Squad 33 taking a blocking position. The incident eventually involved 3 ambulances. Company 33 remained on scene until the wreckage was cleared. This incident created a traffic mess on Rt11 NB as well.