Hundreds of rescuers broke through walls of rock Monday in a desperate race to reach six coal miners trapped 1,500 feet below ground by a cave-in so powerful authorities initially thought it was an earthquake.
Hours after the collapse, searchers had been unable to contact the miners and could not say whether they were dead or alive.
If they survived, a mine executive said, they could have enough air and water to last several days.
"We're going to get them," said Robert E. Murray, chairman of Murray Energy Corp. of Cleveland, a part owner of the Crandall Canyon mine. "There is nothing on my mind right now except getting those miners out."
The mining crew was believed to be about four miles from the mine entrance. Rescuers were working to free the men by drilling into the mine vertically from the mountaintop and horizontally from the side, Murray said.
If they are able to open an old mine shaft, he added, rescuers believe they can get within 100 feet of the men's location.
Doug Johnson, director of corporate services at an affiliated company, UtahAmerican Energy, said rescuers had made "decent progress," but they were not much closer to the men.
Federal mine safety inspectors, who have issued more than 300 citations against the mine since January 2004, were on hand to help oversee the search.
The mine is built into a mountain in the rugged Manti-La Sal National Forest, 140 miles south of Salt Lake City, in a sparsely populated area. University of Utah seismograph stations recorded seismic waves of 3.9 magnitude early Monday in the area of the mine, causing speculation that a minor earthquake had caused the cave-in. Scientists later said the collapse at the mine had caused the disturbance.
"There is no evidence that the earthquake triggered the mine collapse," said Walter Arabasz, director of the seismography stations.
Murray disputed those findings, saying the epicenter was a mile from the trapped miners. "The whole problem has been caused by an earthquake," he said.
Government mine inspectors have issued 325 citations against the mine since January 2004, according to a quick analysis of federal Mine Safety and Health Administration online records. Of those, 116 were what the government considered "significant and substantial," meaning they are likely to cause injury.
The 325 safety violations is not unusual, said J. Davitt McAteer, former head of the MHSA and now vice president of Wheeling Jesuit University in West Virginia.
"It's not perfect but it's certainly not bad," McAteer said. "It would be in the medium range."