Teams of rescuers frantically cleared debris from underground tunnels early Tuesday, trying to reach six coal miners trapped by a cave-in beneath more than 1,500 feet (457 meters) of solid rock.
In early morning darkness, workers in hard hats came and went along a road leading to the mine in a forested canyon among mountains.
"Right now I can't say if it's looking any better," said one weary miner, Leland Lobato, as he ended an eight-hour shift. "They're doing what they can to keep everybody as fresh as possible so nobody gets tired."
The trapped miners were believed to have been in a chamber 3.4 miles (5.5 kilometers) inside the Crandall Canyon mine. Rescuers were able to reach a point about 1,700 (518 meters) from that point before being blocked by debris.
Crews hope drill rigs can punch holes in the mine to improve ventilation and help them determine if the miners survived the early Monday collapse, said Robert E. Murray, chairman of Murray Energy Corp. of Cleveland, a part owner.
"They could have been struck by material and injured or killed, but we don't know that yet," Murray said.
If they are alive, the miners would have plenty of air because oxygen naturally leaks into the mine, Murray said. The mine also is stocked with drinking water.
If rescuers can open an old mine shaft, they think they can get within 100 feet (30.5 meters) of where the men were believed to be, Murray said.
The collapse was reported about 4 a.m. Monday, and relatives of the miners spent the rest of the day waiting at a senior center for news.
Many of the family members do not speak English, so Huntington Mayor Hilary Gordon hugged them, put her hands over her heart and then clasped them together to let them know she was praying for them, she said.
"Past experience tells us these things don't go very well," said Gordon, whose husband is a former miner.
Outside the senior center, Ariana Sanchez, 16, said her father Manuel Sanchez, 42, was among the trapped miners. She said she cried when her mother told her the news, and declined to say more. No details were available about the other miners.
The mine is built into a mountain in the rugged Manti-La Sal National Forest, 140 miles (225 kilometers) south of Salt Lake City, in a sparsely populated area.
Federal mine-safety inspectors, who have issued more than 300 citations against the mine since January 2004, were helping oversee the search.
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. But later, they said a natural earthquake could not be ruled out and more information was needed to conclusively determine what happened.
The mine uses a method called "retreat mining," in which pillars of coal are used to hold up an area of the mine's roof. When an area is completely mined, the company pulls the pillar and grabs the useful coal, causing an intentional collapse. Experts say the technique is one of the most dangerous in mining.
The mining company enlisted the help of 200 employees and four rescue crews, and brought in all available equipment from around the state.
A helicopter was expected to help aim a large drill that can burrow in from the top of the mountain. Another drill was to bore horizontally. A conveyor belt was being installed to clear out collapsed material.
Government mine inspectors have issued 325 citations against the mine since January 2004, according to an 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.
Having 325 safety violations is not unusual, said J. Davitt McAteer, former head of the MSHA and now vice president of Wheeling Jesuit University in West Virginia. "It's not perfect but it's certainly not bad."
This year, inspectors have issued 32 citations against the mine, 14 of them considered significant. Last month, inspectors cited the mine for violating a rule requiring that at least two separate passageways be designated for escape in an emergency.
It was the third time in less than two years that the mine had been cited for the same problem, according to MSHA records. In 2005, MSHA ordered the mine owners to pay US$963 for not having escapeways. The 2006 fine for the same problem was just $60.
Overall, the federal government has ordered the mine owner to pay nearly $152,000 in penalties for its 325 violations, with many citations having no fines calculated yet. Since January, the mine owner has paid $130,678 in fines, according to MSHA records.
Asked about safety, Murray told reporters: "I believe we run a very safe coal mine. We've had an excellent record."
Utah ranked 12th in coal production in 2006. It had 13 underground coal mines in 2005, the most recent statistics available, according to the Utah Geological Survey.
Last summer, Congress tried to make coal mining safer, assessing hefty fines for rule violations and requiring more oxygen to be stored underground. The changes were in response to the Sago mine disaster that killed 12 miners in West Virginia.