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An Arizona man recounted how his vacation at Yellowstone National Park "took a turn for the worst" on Monday when a bison charged his fiancée, tossing her as high as 10 feet in the air.

Chris Whitehill told FOX10 Phoenix how the first day of his trip with fiancée Amber Harris started out beautiful as the couple got coffee and walked through a field near the Lake Lodge Cabins on the north shore of Lake Yellowstone.

But then the Phoenix couple spotted two bison about 50 to 60 yards away.

"[One bison] scratched at the ground and I started screaming and yelling and trying to distract him and he charged at Amber, hitting her square in the abdomen," Whitehill said. "I looked over my shoulder and she was 8 to 10 feet in the air and landed right on her back." 

YELLOWSTONE NATIONAL PARK VISITOR SEEN TAKING SELFIE INCHES FROM BISON IN VIDEO

Bison and danger sign

Visitors are urged to stay at least 25 yards from bison, which can run three times faster than humans, park officials said. (National Park Service / Jacob W. Frank)

The 47-year-old Harris was gored and suffered significant injuries to her chest and abdomen, the National Park Service said. She was airlifted to Eastern Idaho Regional Medical Center. 

Whitehill said Harris suffered seven fractured vertebrae and two partially collapsed lungs.

"It’s hands down the most difficult thing I’ve witnessed," he said. "And praise God she won’t have to have surgery, but it is going to be a long road to recovery for her."

Whitehill also recalled the incident to NBC’s "Today," calling it a "freak accident."

"[The bison] had struck her head-on, and she was airborne," Whitehill said. "I think she did like one or two back flips in the air."

Park officials have said it is unclear how close the visitors were to the bison when the animal charged.

YELLOWSTONE NATIONAL PARK OFFICIALS SAY MAN DISTURBED BABY BISON, RESULTING IN ITS DEATH

On Saturday, a bison also severely injured a Minnesota woman in Theodore Roosevelt National Park in North Dakota, the park service said. She was in serious but stable condition after suffering "significant injuries to her abdomen and foot." Exact details of the woman’s encounter with the animal are unknown.

Grazing bison

The bison goring in Yellowstone was the second such attack within days at a U.S. national park. On Saturday, a bison severely injured a Minnesota woman at Theodore Roosevelt National Park in North Dakota. (AP Photo/Blake Nicholson, File)

The NPS warns visitors to stay at least 25 yards away from all wildlife, including bison. Visitors are urged to use extra caution during mating season, which runs from mid-July to mid-August, when bison can quickly become agitated.

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Park officials have said bison have injured more visitors in Yellowstone than any other animal. The park described bison as unpredictable and noted that the animals can run three times faster than humans.