RS18 was first on the scene of the one car spin-out crash that was blocking the left and left-center lanes. RS 18's driver took a blocking position, which in hindsight probably prevented serious injury to rescue personnel and the people involved in the original collision. The crew exited the vehicle to check on the dispatched collision. Approximately 30 - 60 seconds after they exited RS18, a vehicle struck RS18 in the rear. An additional vehicle then collided with the vehicle that struck the squad. Due to the wet road conditions, a third collision occurred shortly after RS18 was struck. Several other "near misses" also occurred while flares were being set-up. The driver of the vehicle that struck RS18 was transported to a regional trauma center. There were no injuries to any rescue personnel.