Huntington, Utah ? After 10 days of setbacks, nerve-jangling “bumps” and a second mine collapse that killed three workers trying to rescue their comrades, authorities Friday conceded defeat to a mountain that appeared to be slowly crumbling.

“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,” federal Mine Safety and Health Administration chief Richard Stickler said as he announced that officials had suspended the rescue operation indefinitely.

The collapse Thursday night killed three rescue workers and injured six others who were trying to tunnel through rubble to reach six men trapped since Aug. 6 after a massive cave-in. Crews on Friday were drilling a fourth hole into the mountain to look for any sign of the missing men.

“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.

Said Utah Gov. Jon Huntsman, who ordered flags lowered to half-staff: “We went from a tragedy to a catastrophe.”

President Bush called Huntsman on Friday afternoon to express his condolences for those who died or were injured in the mine rescue.

The cave-in was believed to be caused by a “mountain bump.” The force from the bump registered a magnitude 1.6 at the University of Utah seismograph stations in Salt Lake City.

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

Stickler said the bump unleashed a massive blast of coal and support material that buried 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.