One man died and another was seriously injured after the two plummeted at least 200 feet down a steep rock canyon wall while climbing Sunday afternoon in the Boulder Falls area.
It took rescuers three hours to extract the surviving climber, who was in critical condition when he was flown to St. Anthony Central Hospital in Denver.
The men, both in their 20s, are thought to be Denver-area residents, authorities said. Their identities were not immediately available.
The men climbed without ropes or safety gear along the wall above North Boulder Creek through an area that is off-limits to climbers, Boulder County sheriff's Lt. Larry Stern said.
"There are all kinds of signs - there's a fence and a wall to keep climbers away," Stern said. "This is a problem area where we average one fatality a year."