The Ontario, or Ontario Shaft, coal mine was started circa 1920 by Ontario Gas Coal Company. In later years it was a mine of Buckeye Coal Co., which was a coal mining subsidiary of Youngstown Sheet and Tube. Sheet and Tube also operated the large and long-lived Nemacolin mine in neighboring Greene County.
1920 Ontario Shaft Explosion
From a Connellsville Weekly Courier article from June 3, 1920 titled, "Six Men are Killed in Blast in Shaft in Washington County:"
"At least six men were killed by an explosion in the coal shaft of the Ontario Gas Coal Company near Cokeburg, Washington County, Pa.
The men were buried under tons of earth and the foreman in charge of the work said he would not be able to tell the exact number of dead until the bodies had been recovered.
The men were employed by the recently formed Ontario Gas Coal Company in sinking a shaft for coal and had reached the top of the coal late yesterday. Soon after they went down the shaft today to resume work there was an explosion which dislodged a great mass of earth and buried every man in the shaft.
The explosion was heard throughout the entire section and miners employed in other mines hastened to the spot. Life saving apparatus of the Bureau of Mines was brought into use but was of no avail.
Forces of volunteer workers were quickly organized to dig out the buried men.
First reports in the Pittsburg stations of the Bureau of Mines were vague as the shaft is some distance from telephones and reports sent out by nearby mining villages were that 30 or 40 men had been killed. Officers of the station left here this afternoon for the scene of the accident."