YELLOWSTONE, WY — (CNN) The sheer size and wildness of Yellowstone National Park’s signature bison provide a magnificent subject for camera-toting tourists.

But officials caution visitors not to come within 25 yards of the animals, noting that they are unpredictable and able to sprint three times faster than people can run.

A 62-year-old Australian man who ventured to within 3 to 5 feet of one bison was seriously injured Tuesday when the animal charged and tossed him into the air several times, park officials said in a statement.

This is the second such incident within weeks.

A 16-year-old Taiwanese exchange student was gored by a bison on May 15 while posing for a photo.

Both encounters occurred in the popular Old Faithful portion of Yellowstone. Tuesday’s was near the lodge. According to witnesses, several people crowded a bison lying near an asphalt path, the park said.

The unidentified man approached the animal while taking pictures, the park said, and the animal came at him. The visitor was taken by ambulance to a hospital; his injuries weren’t considered life-threatening.

In the May incident, the teen girl was visiting Yellowstone with her host family.

As they were hiking near the Old Faithful Geyser, they stopped where a group of people had gathered to watch a bison grazing next to the trail.

“The girl turned her back to the bison to have her picture taken when the bison lifted its head, took a couple steps and gored her,” the Park Service said.

The family was believed to have been standing between 3 feet and 6 feet from the animal, the park service said. She, too, sustained serious injuries.

Every year, some visitors to Yellowstone are gored by bison, sometimes fatally, according to the park service.

“Visitors are reminded that Yellowstone wildlife is wild,” it said. “Wildlife should not be approached, no matter how tame or calm they appear.”

The park is dotted with signs warning people not to get too close to animals. The bison population in Yellowstone is estimated to range between 2,300 to 5,000.

The park’s website details efforts to manage the herd and restore the species.

“Bison are a migratory species, and they move across a vast landscape,” the park says. “When they are inside Yellowstone, they have unlimited access to every square inch of habitat.”

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