HUNTINGTON, Utah — The desperate underground drive to reach six trapped miners was suspended indefinitely Friday after a cave-in killed three rescuers inside a mountainside mine.

“Is there any possible way we can continue this underground operation and provide safety for the rescue workers? At this point we don’t have an answer,” said Richard Stickler, head of the federal Mine Safety and Health Administration.

The collapse Thursday evening killed three rescue workers and injured at least six others who were trying to tunnel through rubble to reach six miners trapped Aug. 6 inside the mountain. Stickler said mine-safety experts were being summoned to central Utah to discuss the crisis.

“Yesterday we went from a tragedy to a catastrophe,” Gov. Jon Huntsman said. He said the state would help federal officials in the investigation into the collapse.

“We have questions, too, and we want answers to those questions. We want to make sure that the lives that were lost last night were not in vain,” Huntsman said.

Outside the mountain, crews were drilling a fourth hole for any sign of the six men, whose survival status still was unknown on the 12th day of confinement, 1,500 feet below ground.

“Without question, we have suffered a setback and we have incurred an incredible loss, but this team remains focused on the task at hand” – the rescue of the miners, said Rob Moore, vice president of Murray Energy Corp., co-owner of the Crandall Canyon Mine.

Notably absent from Friday’s news conference was the co-owner of the mine, Bob Murray, whose emotional speeches have dominated the news of the six trapped miners.

“He wanted to be here. I’m certain you understand the reasons he could not be here this morning,” Moore said. He provided no details on where Murray was.

As for the effort to drill down into the mountain, Stickler said the fourth borehole had reached 600 feet below the surface, with 900 feet to go before it reaches the mine. Officials are aiming for the spot where mysterious vibrations were detected for a few minutes Wednesday.

“We hope to find the miners alive when that borehole goes into the mine. We can keep them alive lowering water and food through the borehole,” he said.

Thursday’s collapse was a devastating turn for the families of the six trapped miners, and for the relatives of those trying to rescue them. All rescue workers were evacuated from the mine Thursday evening and work underground was stopped.

The cave-in at 6:39 p.m. was believed to be caused by a “mountain bump,” in which shifting ground forces chunks of rock from the walls. The force from the bump registered a magnitude of 1.6 at the University of Utah seismograph stations in Salt Lake City.

Stickler said it unleashed a huge blast of coal and support material that hit the miners working to clear rubble from the underground tunnel. The blast created a destruction zone about 30 feet long along a wall of the chamber, and knocked out steel posts, chain link fencing and the cables that tied everything together.

“When that energy gets released, it’s like an explosion,” Stickler said.

The force from the bump registered a 1.6 at the University of Utah seismograph stations in Salt Lake City, said university spokesman Lee Siegel. It was the 20th reading at the university since the original collapse, which registered a 3.9 on Aug. 6.

“These events seem to be related to ongoing settling of the rock mass following the main event,” Siegel said Friday morning. “I don’t think I’m going too far to say that this mountain is collapsing in slow motion.”

The Aug. 6 collapse led to the frenetic effort by rescuers to dig through the mine toward the men and drill narrow holes atop the mountain in an attempt to learn their whereabouts and perhaps drop food and water.

Underground, rescuers had advanced only 826 feet in nine days. Before Thursday’s cave-in, workers still had about 1,200 feet to go to reach the area where they believe the trapped men had been working.

Mining officials said conditions in the mine were treacherous, and they were frequently forced to halt digging because of seismic activity.

One of the workers killed in the Thursday cave-in was a MSHA inspector, agency spokesman Dirk Fillpot said. He did not know his name or have information about the other victims.

Injuries to the survivors ranged from cuts and scrapes to head and chest trauma.

One rescuer died after being taken to Castleview Hospital in Price, and another died at Utah Valley Regional Medical Center in Provo, according to hospital spokespeople. The third death was confirmed by Rich Kulczewski, a U.S. Department of Labor spokesman.

Three injured miners were released from Castleview on Friday morning, and a fourth remained there in serious condition with back injuries, hospital chief executive Jeff Manley said. Another miner was in serious condition with head trauma at the Provo hospital, and a sixth was in fair condition at University of Utah Hospital in Salt Lake City.

The president of the United Mine Workers of America, Cecil E. Roberts, blamed the mine’s owners and federal officials for the latest tragedy. Owners of the nonunion mine had rejected UMW offers to help in the rescue effort, saying they had all the help they needed.

“This disaster has only compounded what was already an immense tragedy. Making the situation much worse is the fact that all of these deaths were needless and preventable,” Roberts said in a statement from union headquarters in Fairfax, Va.

Three of the trapped miners are from Mexico, and Mexico’s consul in Salt Lake City, Salvador Jimenez Munoz, said he urged the governor to continue the rescue effort. While experts need to study the best way to do it safely, “this effort should not be interrupted,” Munoz said.

Susana Salcido sobbed when told Friday that the search for her cousin Manuel Sanchez and the other miners had been suspended indefinitely.

“Yesterday we were hopeful after learning that they had heard noises (inside the rubble),” said Salcido, who lives in Sanchez’s home town of Nuevo Casas Grandes.

“We never imagined that instead of good news we would hear about another tragedy,” she added, referring to the killed rescuers.

Even so, she said she is not ready to lose hope.

“All we can do now is pray for a miracle,” Salcido said.