On June 4th, 1989, about 47 miles east of the Russian city of Ufa, a passenger train carrying 1300 vacationers was engulfed in an enormous explosion equivalent to about 300 tons of TNT.

A gas pipeline carrying propane and butane had sustained damage after being struck by an excavator. Due to the cancellation of a real-time leak detection system and a patch of still weather, the gas was rapidly able to accumulate in the lowlands surrounding the railway tracks. As the train passed through this low point, sparks from the wheels ignited the gas pocket resulting in the explosion. 575 people were killed, some instantly and many others in the hospital. In total, 800 people were wounded. 

This tragic event was the second most deadly rail disaster in Russian history.