Rangers from Rocky Mountain National Park said they have not found any evidence of a threat after a man ran through the park last week yelling that he was being chased by someone with a rifle.

The incident happened on Thursday on the Gem Lake Trail. Visitors called park rangers to report that a man was running toward the Lumpy Ridge Trailhead parking area screaming in terror and yelling about being chased.

The running man even knocked down a woman who was hiking up the trail, causing her to sustain minor injuries and be taken to a hospital via ambulance, officials said.

Responding park rangers found the man sitting on the ground about 400 yards from the trailhead.

The man appeared to be injured and under the influence of an unknown substance, officials said. The rangers detained the man, who was described as “combative,” and sent him to a hospital for treatment.

While at the hospital, it was determined that the man was under the influence of narcotics, officials said.

Rangers searched the park and interviewed around 30 people on the trail with help from the Estes Park Police Department and its K-9 unit. No weapons were found and no one reported seeing someone with a gun or hearing any gunshots.

Rangers located two men on the trail who said they were visiting the park with the suspect and that the group of three were there to hike at Lumpy Ridge. Those men were escorted off the trail and questioned.

The incident is currently under investigation. Park rangers are working with the U.S. Attorney’s Office to determine if charges will be filed against the man.