Rescuers pushed deeper into a mineshaft in a desperate search for 13 trapped coal miners Tuesday, but the prospects of finding anyone alive appeared bleak after holes drilled into the ground yielded deadly levels of carbon monoxide and no signs of life. "With each hour that passes the likelihood of a successful outcome diminishes," said Ben Hatfield, chief executive of mine owner International Coal Group Inc. Hatfield said earlier Tuesday that holes drilled into the ground yielded deadly levels of carbon monoxide and there were no signs of life. By early evening, Hatfield said rescuers were three to five hours from reaching where the miners were last located in the Sago Mine, about 100 miles northeast of Charleston. "We are clearly in the situation where we need a miracle," Hatfield said. "But miracles happen."