Man recovering from surgery after bison attack at Yellowstone, as experts share safety warning

A man is recovering from surgery after he was tossed into the air by a bison at Yellowstone National Park in Wyoming.

The unidentified man was seen walking with his grandson when the bison charged at him and threw him up into the air after he attempted to run away from the massive animal.

Campers first noticed the lone bison amid the tents at Bridge Bay Campground as it began to run around the site, and shouted to warn others.

Mike MacLeod, a local park photographer who witnessed the attack and captured it on video, told ABC News he "really didn't think [the bison] was going to pickthose two people of all the people who were even way closer."

In the video, the bison can be seen resting on the grass. As the grandfather and his grandson stop to take a photo, the bison stands up and the pair attempt to flee.

The grandfather is seen running around a few trees, but the bison soon catches up and tosses the helpless visitor eight feet in the air.

"The bison was pumping his legs and pumping his head and exhibiting very aggressive behavior," Mcleod said.

The photographer attempted to distract the bison by yelling and jumping up and down, then put down his camera to rush and assist the injured man.

"He was in a lot of pain and he was trying to not move his leg, but his immediate concern was for his grandson," Mcleod said.

The grandson was shaken but doing OK, according to Mcleod.

He told ABC News he's been in touch with the grandfather's family, who said he had a successful surgery and is expected to recover.

No information on the incident has been released by the National Park Service and the agency did not immediately respond to ABC News' request for comment.

According to park officials, "Bison have injured more people in Yellowstone than any other animal."

"They are unpredictable, can run three times faster than humans and will defend their space when threatened," the national park stated. "Wild animals can be aggressive when people do not respect their space. Visitors are responsible for staying at least 25 yards away from all large animals, including bison, elk, bighorn sheep, deer, moose and coyotes."

Wildlife expert and Zoo Miami Foundation conservation liaison Ron Magill told ABC News that summer can be a particularly dangerous time of year to be around male bison.

"We're at the peak of what's called the bison rut," he said. "This is where the males are just raging in hormones because they're fighting for territories and they're fighting for females."

For other visitors who encounter bison, Magill offered some advice.

"The key thing to do is to move away slowly, do not run, do not make any fast types of movements," he said.