HUNTINGTON, Utah (CNN) -- Rescue workers trying to reach six men trapped in Utah's Crandall Canyon mine found survivable space Saturday after punching a second, wider hole into a cavity where the workers are believed to be trapped and lowering a camera, a federal official said.
This camera, which was sent into the mine, has a lens on its end and one on its side.
But efforts to signal the miners were once again met with silence.
Richard Stickler, director of the U.S. Mine Safety and Health Administration, said the camera -- which showed vertical images -- is being pulled out.
The lens will be cleaned and a "horizontal lens" installed so the camera can be lowered again in the hope of getting images of a broader area, Stickler said.
The first images of the cavity showed a 5½-foot void with the roof line intact and about two feet of broken coal mixed with some water on the mine floor, he said. Compressed air is being pumped into the area through the hole.
Rescue workers pounded on the drill steel several times. Miners are trained to respond to these series of taps as loud as they can on anything metallic, but there was no reply.
"We're very disappointed we didn't get a response," said Mike Glasson, an engineer and geologist with Murray Energy Corp.
"The activity is of a very fast pace, but progress is way too slow for me, and I think for anyone, but it's not because of effort," Bob Murray, president and CEO of Murray Energy Corp., told reporters. Watch how efforts to find the miners have come up empty so far »
Officials met twice with family members Saturday. The brother of trapped miner Don Erickson sounded discouraged as he emerged from one of the sessions. "Same stuff," said Terry Erickson. "I'm getting tired of hearing it."
Tomas Hernandez, uncle of 23-year-old Luis Alonso Hernandez, told a reporter in Spanish that it was best to become resigned to the miners' likely fate: "As time goes by, we are losing hope."
Some of the miners at Crandall Canyon -- including one of the trapped men -- apparently were concerned about working in the area of the collapse, a source told CNN.
The source, who requested anonymity, said the six trapped miners were working in an area called 7 Belt -- the deepest part of the mine.
In recent weeks, the floors in that part of the mine had been "heaving," or buckling up, from intense pressure, said the source, who has intimate knowledge of the conditions in the mine.
Supervisors at the mine knew of the problem, he said.
Several miners -- reportedly including Manuel Sanchez, who is among the trapped men -- were becoming apprehensive, the source said.
A member of Sanchez's family told a Utah newspaper that he had expressed concern about safety in one part of the mine.
The mine's operator said he was not aware of the safety concerns.
"I've never heard that," Murray told CNN's Ted Rowlands when asked why someone would have been worried about that section of the mine. "I have no idea. It's probably a rumor, and I'm not going to respond to rumors."
Sanchez has been trapped since early Monday, along with five other miners. The mining company has not released the miners' names, but family and friends have confirmed to CNN the identities of Sanchez, Kerry Allred, Carlos Payan, Brandon Phillips, Alonso Hernandez and Erickson.
Asked why they did not complain about their safety concerns, several miners said complaining means the loss of a job.
Murray denied that. "If you're getting that from the community, then those miners must work for another mining company. I don't operate that way," he said.
Not so, said Paul Riddle, who used to work in one of Murray's mines. "Always profits before safety, that's my opinion, my feeling, my experience," he said.
Miners who work for Murray are sometimes forced to push the envelope when it comes to safety, he said, and are afraid to speak up for fear of being fired.
"I'm not the only one," he said. "There are many, many people that feel this way and are afraid to speak up."
An attempt to make contact with the trapped miners was unsuccessful Friday, when a microphone lowered into a narrow hole drilled into a mine cavity detected no sounds. Murray said that technical difficulties prevented the microphone from picking up sound, the drill steel was blocking the microphone, and a line broke.
There has been no communication with the miners since the collapse.
Air tests overnight suggested there may be oxygen levels of about 20 percent in the area where the miners are thought to be, Stickler said. Later tests found oxygen levels at about 7 percent -- too little to survive -- but that may be because the drill hole drifted as it was being bored, Stickler said. See where the miners are thought to be trapped »
Murray said Thursday that if the miners survived the collapse, they could continue to live on fresh air, food and water supplied through the holes until crews can remove tons of coal and rock that clogged a collapsed tunnel.
That process could take four or five more days, he said early Friday.
Between what they had packed with their lunches and what was stored in the mine, the men had about a week's worth of water, Murray said. See the rescue efforts at the mine »
Murray has insisted a magnitude-3.9 earthquake caused the mine collapse, and has said at least 10 "aftershocks" have been recorded, with seismic activity earlier wiping out more than 300 feet of progress and halting rescue efforts temporarily.
Seismologists and geophysicists have not been as sure, saying the seismic activity they measured appeared to stem from the mine's collapse.
Experts have said the "aftershocks" could be the rock adjusting after the collapse.
About 50 representatives of the Mine Safety and Health Administration are on the site, Stickler said. He said the mine is in compliance with federal laws.
Inspectors cited it for 30 violations this year, MSHA records show. Recommended fines in the 10 cases involving penalties ranged from $60 to $524. E-mail to a friend
CNN's Vivienne Foley, Ed Lavandera and Gary Tuchman contributed to this report.