[chris]

On June 4, 1989, a faulty 900-meter pipeline in the Soviet Union leaked liquid propane and butane. The gas collected in low-lying ground near a railway line.

At about 1:15 a.m., sparks ignited the gas as two passenger trains carrying about 1,300 vacationers passed through the area. The explosion destroyed train cars and scattered wreckage across the site.

More than 575 people died immediately. Blast estimates ranged from 200 to 300 tons of TNT equivalent, with one calculation placing it as high as 10 kilotons.