Ufa train disaster: A natural gas explosion near Ufa, Russia, kills 575 as two trains passing each other throw sparks near a leaky pipeline.

The Ufa train disaster was a railway accident that occurred on 4 June 1989, in Iglinsky District, Bashkir ASSR, Russian SFSR, Soviet Union, when a gas pipe explosion killed 575 people and injured 800 more. It is the deadliest rail disaster during peacetime in Soviet/Russian history and the second-deadliest overall after the Vereshchyovka train disaster. This accident took place exactly a year after the 1988 Arzamas train disaster.

Natural gas is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium. Methane is a colorless and odorless gas, and, after carbon dioxide, is the second-greatest greenhouse gas that contributes to global climate change. Because natural gas is odorless, a commercial odorizer, such as Methanethiol, that smells of hydrogen sulfide is added to the gas for the ready detection of gas leaks.

Ufa is the capital and largest city of Bashkortostan, Russia. The city lies at the confluence of the Belaya and Ufa rivers, in the centre-north of Bashkortostan, on hills forming the Ufa Plateau to the west of the southern Ural Mountains, with a population of over 1.1 million residents, up to 1.4 million residents in the urban agglomeration. Ufa is the tenth-most populous city in Russia, and the fourth-most populous city in the Volga Federal District.