10/12/1896 - Stockton Mine - Explosion / Spontaneous Combustion

In the Stockton Mining Disaster of 1896, nine men died from gas inhalation while trying to determine the cause of a gas leak that killed two men a few days earlier. It was discovered that spontaneous combustion caused a fire that produced the gasses that killed these men. 

The death of the rescuers highlighted the need for special breathing equipment for rescue operations.