Station 90 was dispatched for a rescue company assist station 84 with an MVC with entrapment involving a school bus.Deputy 84 (C.Lockwood) arrived on scene to find a 3 vehicle MVC with 1 patient trapped. Deputy 84 established command and declared a level 1 MCI. Rescue 90 responded with a crew of 4 and arrived as the 1st due rescue. Rescue 90 assisted with patient care and debris clean up. Crews operated for 1 hour. A total on 5 patients were transported Great work by all who assisted. Scene turned over to DSP for investigation. Units on scene: R-90, 84-1, 84-4, Rescue 84, Utility 90, C-84, A-84, C-90, B-70, Medic 105, EMS 25, fire police, and DSP.