 The mine was considered to be the safest in the region and according to reports, was free from the gases that plagued so many other coal operations.On May 1, 1900, an errant spark touched off the fine haze of coal dust deep underground, and the Winter Quarters #4 mine exploded with fury.Exactly 100 of the men were killed in an instant, and another 99 died from the poisonous afterdamp, making this one of the worst coal mine disasters in history.