A 68-year-old hiker in Rocky Mountain National Park was killed in a freak accident when a tree fell on him.

William Hudson, of Boulder, Colorado, died Tuesday when he was hit by the falling tree and subsequently fell and hit his head on boulder on the side of the trail.

Mr. Hudson was hiking with Carl Cox, also of Boulder, who was slightly injured by the tree fall but was able to go for help. The two were on the Sandbeach Lake Trail at the time.

Rangers say the tree was a 50-foot tall Douglas fir that snapped off about 15 feet above the ground due to tree rot. After glancing off three standing trees the fir struck the two men. The section of tree that hit the men was about 10 inches in diameter, according to park officials.

Tree falls are an occasional hazard in the backcountry of parks. Often they're associated with "snags" -- trees killed by fire but which remain standing until the right mix of circumstances knocks them down.