The Helena Train Wreck occurred in the early morning on February 2, 1989, in Helena, Montana, USA, when 48 cars of a Montana Rail Link freight train that had been decoupled from their locomotives by a train crew on Mullan Pass rolled backwards down the pass, traveling nine miles back into the city of Helena and colliding with a work train at a railway crossing near the center of the community. The collision resulted in a fire and explosion that damaged Carroll College and other nearby structures, knocked out power to most of the town, and led to the evacuation of residents within an area of due to concerns of possible toxic chemical release. The event occurred during a severe cold snap, with temperatures below that morning and with a wind chill factor of as much as , which froze the water that firefighters used to attempt to extinguish the fire.