MEDORA, N.D. (AP) — A teenage visitor to a national park in North Dakota has been injured by a bison.

Officials at Theodore Roosevelt National Park say the 17-year-old victim from Colorado was on a trail Saturday and walked between two bull bison that had been fighting. One bison charged the teen who was struck in the back, gored in the thigh and tossed about six feet in the air.

Park rangers and Billings County paramedics treated the teen at the scene until the victim could be taken by helicopter to a Bismarck hospital. Authorities say the teen is in stable condition.

Park regulations require that visitors stay at least 25 yards away from large animals such as bison, elk, deer and horses.