HUNTINGTON -- Underground efforts to reach six miners trapped in central Utah's Crandall Canyon mine since Aug. 6 have been suspended indefinitely following a Thursday night cave-in that killed three rescue workers. Richard Stickler, assistant secretary of Labor over the federal Mine Safety and Health Administration, said efforts deep inside the coal mine would remain halted unless some way is found to safely resume them. "This was a tragic accident [that] was the result of seismic activity, a mountain 'bump,'" he said at a late-morning briefing near the mine. "We had put in the strongest ground-support system . . ....