The State Fire Marshal’s Office says a leak in a propane line caused the explosion at the L.E.A.P. building in Farmington last week that killed a firefighter and injured several others.

Investigators say they located the leak in the propane line which was buried under the paved parking lot.

The report shows the leaked propane permeated the ground under the parking lot and some of that gas then made its way into the basement.

The propane tank had been filled Friday, September 13, with nearly 400 gallons of propane but the tank was empty on Monday morning, prior to the explosion, when it was examined by maintenance supervisor Larry Lord and another employee.

Investigators say Larry Lord was in the basement with Farmington firefighters “TD” Hardy, Joseph Hastings and Scott Baxter when the explosion took place.  Fire Captain Michael Bell was on the first floor, Fire Chief Terry Bell was near the rear door of the building, and Deputy Fire Chief Clyde Ross and Firefighter Ted Baxter were outside the building in the parking lot.

More than 100 interviews have taken place as fire marshals continue to work with the Bureau of Alcohol, Tobacco, Firearms and Explosives, Farmington police and fire departments and the Maine Solid Fuel Board.