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 girl from Colorado was on a trail Saturday and walked between two bull bison that had been fighting. One bison charged the teen. She was struck in the back, gored in the thigh and tossed about 6 feet (2 meters) into the air.

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

Park regulations require that visitors stay at least 25 yards (22.85 meters) away from large animals such as bison, elk, deer and horses.