1989 Helena train wreck
The Helena Train Wreck occurred in the early morning on February 2, 1989, in Helena, Montana, United States, when 49 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 set of "helper" locomotives 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 2 square miles (5.2 km2) due to concerns of possible toxic chemical release.