1945 El Teniente mining accident Wikipedia
The 1945 El Teniente mining accident, known locally as the Smoke Tragedy (Spanish: La tragedia del humo) is the biggest metallic mining accident in the history of Chile. It happened on June 19, 1945, in Chile's El Teniente mine, which belonged to Braden Copper Company at the time; 355 men died. Many of the miners died of carbon monoxide poisoning as a result of a fire that broke out near the mine, trapping the workers. Along with improperly marked emergency exits, the workers were unable to escape the flames. Rescue workers spent 3 days to try and free the miners, although it was to no avail.