The body of one coal miner has been found in a West Virginia mine, more than a day and a half after 13 miners were trapped following an explosion.
The fate of the other 12 miners is unknown.
Ben Hatfield, the head of the mining company, International Coal Group, Inc., said rescue crews also found the miners' transport bus in a tunnel. He said it appears that the miners left the bus on their own power, which he says is a good sign because they could have headed toward safety.
Air quality tests show a higher level of carbon monoxide than humans could tolerate. But Mr. Hatfield has noted the miners' emergency techniques - such as barricading themselves against the gases - may have kept them safe.
Rescue crews are continuing to operate, and have already advanced about 3,500 meters.
The miners have not been heard from since early Monday.
Some information for this report provided by AP and Reuters.