The boy is in stable condition. The big cat was later killed by wildlife wardens.
Kyle Burgess said he'd stumbled upon the mountain lion's cubs during a trail run in Utah's Slate Canyon.
There have been four mountain lion attacks on children in California over the past 16 months.
A brave Southern California woman tried to pry open a mountain lion's jaws as it attacked her dog in her Simi Valley backyard.
A Sonora, California, couple had an uninvited guest who really hogged the toilet.
The span along U.S. 101 will only be the second animal overpass in the state.
They could vanish in 50 years – or be protected by "wildlife corridors," researchers say.
The man, who was running alone at Horsetooth Mountain, killed the young lion by choking it.
The Living With Lions project hopes that the more people in Northern California know about the apex predators, the more they'll respect them.
The loss of the famed cougar is one more reason for a California wildlife corridor to protect the big cats, animal advocates say.