A woman in Yellowstone National Park was injured by a bison Wednesday afternoon, but declined to be taken for additional medical care.

Park officials did not release full details of the incident, but said the woman approached too close to the bison, within 25 yards, somewhere in the Upper Geyser Basin, which is home to Old Faithful.

The incident remains under investigation, and is the first bison-related injury of the year. Yellowstone opened Monday for the season, offering only restrooms and self-service gasoline, with no overnight accommodations.

Park emergency medical providers responded to the incident immediately, according to a statement released by the park’s public affairs office. She was assessed and refused transport to a medical facility.

Park managers remind visitors that wildlife in Yellowstone National Park are wild. When an animal is near a trail, boardwalk, parking lot, or in a developed area, give it space. Stay 25 yards away from all large animals, and at least 100 yards from bears and wolves.

Additional information about safety in the park is available online.