HUNTINGTON, UTAH (CBS/AP) -- Efforts to reach six coal miners trapped more than 1,500 feet underground will take at least three days, and rescuers weren't even sure the men had survived the cave-in, one of the mine's owners said Tuesday.
Crews worked through the night in shifts, with teams coming and going along the road leading to the Crandall Canyon mine in a forested canyon.
"Progress has been too slow, too slow," said Robert E. Murray, chairman of Murray Energy Corp. of Cleveland, a part-owner of the Crandall Canyon mine.
If all goes well, it will still take three days to reach the chamber where the miners are believed to be, he said.
"At that point we will know whether they're alive or dead," Murray said.
Even then, rescuers will have only a two-inch hole into the chamber through which to communicate with the miners and provide them food or air, he said.
Crews moved only 310 feet closer to the miners in the first 30 hours after the cave-in, Murray said.
Attempts were halted overnight after a "bump" in which coal was dislodged from the mine's ribs, said Al Davis, an official with the Federal Mine Safety Health Administration.
The trapped miners were believed to be in a chamber 3.4 miles inside the mine. Rescuers were able to reach a point about 1,700 feet from that point before being blocked by debris.
With no way to know whether the six were alive, crews worked through the night in shifts. Workers in hard hats came and went along a road leading to the mine in a forested canyon among mountains. Dozens of trucks and cars headed in near dawn.
"Right now I can't say if it's looking any better," weary miner Leland Lobato said. "They're doing what they can to keep everybody as fresh as possible so nobody gets tired."
Several other miners emerged with blackened cheeks after an all-night shift.
Two C-130s from the 911th Airlift Wing of the Air Reserve in Pittsburgh were being sent seismic equipment and staff, Pentagon spokesman Bryan Whitman said.
Murray said there were 30 pieces of "massive" mining equipment in place and 134 people dedicated to the rescue.
He insisted that an earthquake caused the cave-in and angrily denied that a method called "retreat mining" was taking place at the time.
In that method, pillars of coal are used to hold up an area of the mine's roof. When that area is completely mined, pillars are pulled to get access to useful coal, causing an intentional collapse. Experts say it is one of the most dangerous mining methods.
"The damage in the mine was totally unrelated to any retreat mining," Murray said.
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 $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."
Murray had earlier expressed optimism that the miners would be rescued. "We're going to get them," Murray said. "There is nothing on my mind right now except getting those miners out."
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.
The Associated Press and CBS News contributed to this report.