Park Rangers rushed to Bridge Bay Campground and administered first aid until medics arrived. The incident is still being investigated.
A full grown male bison could weigh more than 2,000 pounds and stand 6 feet tall, while females can weigh 1,000 pounds and stand 4 to 5 feet tall. The animals can reportedly reach speeds up to 35 mph.
In May, a bison knocked down a tourist in the Old Faithful Upper Geyser Basin, NBC reported. In July 2019, a 9-year-old girl was launched into the air by a bull bison, although she was not seriously injured. The group she was with had been standing dangerously within 5 to 10 feet of the animal, according to the reports.
Also roaming the vast 3,472-square-mile wilderness of Yellowstone are bears, wolves, elk, bighorn sheep, deer, moose and coyotes.
Park visitors are told to stay at least 100 yards from bears and wolves.
Just last week, a 37-year-old Missouri woman hiking on the Fairy Falls Trail near Old Faithful was clawed during a close encounter with a female grizzly.