Arzamas explosion, known also as Arzamas train disaster occurred on June 4, 1988, when three goods wagons transporting hexogen from Dzerzhinsk to Kazakhstan exploded on a railway crossing in Arzamas, Gorky Oblast, USSR (now Nizhny Novgorod Oblast, Russia).
Explosion of 118 tons of hexogen made a 26 metre deep crater (85 ft), caused major damage in the city, killing 91 people and injuring 1,500. 151 buildings were destroyed.
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Arzamas train disaster Wikipedia(Text) CC BY-SA