A Consol Energy mine on the West Virginia-Pennsylvania line remains closed while officials check for a suspected underground fire that prompted the mine's evacuation.
Consol officials say elevated carbon monoxide levels in the Blacksville No. 2 mine shaft "suggest that we have smoldering or the possibility of a fire in the mine."
More than 120 day-shift workers were safely evacuated when the smoke was first spotted Tuesday afternoon.
Mine Safety Health Administration spokeswoman Amy Louviere says the agency's inspectors were at the mine at the time and ordered the evacuation. She says mine rescue teams withdrew when they felt heat and encountered heavy smoke, though the source hasn't been pinpointed.
The mine employs about 650 workers and produces coal for power plants.
The mine is in West Virginia, though its shaft portals are in Greene County, Pa.
Copyright 2013 The Associated Press.