Portions of the park will be closed this weekend as rangers try to find and euthanize the mountain lion.
In a matter of seconds, Lindsey Grewe went from jogging on the trail to running for her life when the mountain lion began chasing her.
"I'm screaming, but I don't think anyone heard me. I really thought he was going to attack me, I just had visions of, I see it crossing through my mind that I was going to get eaten," Grewe said.
Park rangers heard Grewe screaming and rescued her.
They say euthanizing the mountain lion is their only option, because the animal is too aggressive to stay in the park.
Earlier Friday, the same mountain lion approached a runner on the trail, but backed off when the man made noise.
He says the animal was eating a deer.
Denver Zoo carnivore area supervisor Steve Venne says the mountain lion was likely defending his kill.
Mountain lions left the zoo in 2009, but Venne spent years caring for them.
As more people move into mountain lion country, Venne says problems arise when the predators get too comfortable around people.
If you come in contact with one, Venne says stand your ground and slowly back away.
"Eye contact, facing the predator, being big, being loud," Venne said.
Venne says you should never turn your back on a mountain lion.
And if one does attack, fight back.
Mountain lions are known to be territorial, but they generally do not consider humans prey.
Park Rangers are warning hikers, climbers and outdoor enthusiasts to be careful in the area.
(KUSA-TV © 2012 Multimedia Holdings Corporation)