Natural gas explosion kills 500 in Russia - Jun 03, 1989 - HISTORY.com

In a freak and tragic accident, a natural-gas pipeline explodes in Russia’s Ural Mountains just as two trains pass it.

The explosion occurred near the town of Ufa in what was then the Soviet Union and was the result of poor judgment by pipeline workers. They were aware that the pressure in the pipeline dropped significantly on June 3—a sign of a possible leak. However, instead of following standard procedure and checking for leaks, they instead pumped more and more natural gas through the line to keep the pressure up. The gas continued to leak and spread through the nearby area, mostly settling in a low area near the rail tracks about a mile from the pipeline.

As this was happening, two trains were approaching on the Trans-Siberian Railway, passing each other near the gas leak. Suddenly, the natural gas ignited, causing a massive fireball to erupt and flames to spread over an area a mile in length. The force of the explosion knocked several train cars right off the tracks. Hundreds of trees in the surrounding forest were instantly incinerated by the extreme temperatures.

The explosion and derailment caused tremendous casualties on the trains. Just over 500 people lost their lives (a precise count could not be made) and many others suffered horrible burns. Helicopters were flown in to evacuate the burn victims quickly to area hospitals.