Colorado is home to up to 4,500 mountain lions, and they sometimes wander into urban areas looking for food, according to wildlife officials

A US woman has saved her five-year-old son's life by prying his head from the mouth of a mountain lion that was attacking the boy in their front yard.

The mother heard screaming while the boy was playing with his brother outside their home near the Colorado resort town of Aspen, Pitkin County sheriff's deputy Michael Buglione said.

She ran outside, saw her son struggling with the animal and rushed to his aid.

"She said the mountain lion was on top of her son, crouched down on top of him," Mr Buglione said. "She grabbed a paw and lifted it up, and put her right hand in its mouth to pry the boy out of its mouth so the boy could get free."

The animal ran off. The boy suffered deep cuts to his face, head and neck and was taken to a Denver hospital, Mr Buglione said. The mother had bite marks on her hand and scratches on her leg. She was treated and released.

The mountain lion was estimated to be about two years old and not fully grown. Wildlife officials killed two mountain lions in the area within several hours of the attack. Both animals were examined to determine if they were hungry, diseased or just in the wrong place at the wrong time.

Colorado is home to up to 4,500 mountain lions, and they sometimes wander into urban areas looking for food, according to state wildlife officials. Since 1990, mountain lions have killed three people and injured 18 in the state.

"They're wild animals. They find habitat where they can forage for food," Colorado Parks and Wildlife spokesman Matt Robbins said. "When you have bunnies, you're likely to find foxes or coyotes. If you have deer, there is a good chance you'll find mountain lions."

The last known lion attack on a human in Colorado occurred in July last year, wildlife officials said. A young lion attacked a man as he fished north of Dotsero, about 60 miles from where the latest attack occurred. The man suffered scratches and bites on his back and was treated at a local clinic and released.

The lion in that incident, described as a small yearling male, was tracked and killed.

PA Media