On March 1, 1944, a train stops in a tunnel near Salerno, Italy, and more than 500 people on board suffocate and die. Occurring in the midst of World War II, the details of this incident were not revealed at the time and remain somewhat murky.

Train Number 8017 left Salerno heading for the rural area south of the city through the Apennine Mountains. Although it was a freight train that was not supposed to carry passengers, it was common at the time for both soldiers and civilians to hitch rides on any convenient train. Passing through the towns of Eboli, Persano and Romagnano, the 8017 had picked up approximately 650 passengers by the time it reached Balvano.

Balvano was a tiny town between two long tunnels in the Apennines. It was raining as the 8017 began to ascend the Galleria delle Armi tunnel pass just outside of Balvano. Almost immediately, it was forced to stop. There were conflicting reports as to why this happened: either the train was unable to pull the overloaded freight cars up the slope or the train stopped to wait for a train descending in the opposite direction. In any case, the train sat idling in the tunnel for more than 30 minutes. While this might not have posed a severe danger in some circumstances, the train’s locomotives were burning low-grade coal substitutes because high-grade coal was hard to obtain during the war and the coal substitutes produced an excess of odorless and toxic carbon monoxide.

Approximately 520 of the train’s passengers were asphyxiated by the carbon monoxide as they sat in the train. The government, in the midst of an intense war effort, kept a lid on the story–it was barely reported at the time although it was one of the worst, and most unusual, rail disasters of the century and came less than two months after a train wreck in the Torro tunnel in Spain killed 500 people.