WTOP News Reports.. Loudoun County barn explodes, burns ‘to the ground’ A barn in Loudoun County, Virginia, was destroyed after an explosion on Friday night, according to a fire official. An old barn on an undeveloped parcel of land in the 45700 block of Maries Road in Sterling was fully engulfed in flames when fire crews arrived on the scene late Friday night. Based on explosion, Caussin said the fire department believes it was possibly from a propane cylinder.