A 17-year-old from Colorado is in stable condition after being gored by a bison while walking along a trail at Theodore Roosevelt National Park in North Dakota, according to park officials.
The teenager was a quarter-mile from the Halliday Well Trailhead Saturday morning when he encountered a bison herd, the park said in a news release Sunday.
Two bull bison that had been fighting with each other were standing on either side of the trail, about 20 feet from each other, as the teenager passed.
"This can happen to anyone," said the injured teenager, who asked to be identified only as a male from Colorado. "I didn't think it was going to happen to me -- I am a very experienced hiker. Like, I wouldn't have put myself in any dangerous situation if I thought it was gonna happen."
"I didn't try to be aggressive towards the bison, I didn't try to get his attention, I wasn't up close, I wasn't trying to take pictures, I was just ... no reason for it," the teen continued. "There was another group of hikers that had just gone past him. ... I didn't feel unsafe at any point while I was around him, and then all of sudden he just came and charged at me."
The 17-year-old said he never lost consciousness, was flung into the air, landing on his backpack.
"I lost my breath, and I had to lay there in a minute of just complete shock, and didn't know what to do," he added. "It just kind of was running, and then all of a sudden, he just throws me into the air. And I was flung about 6 feet into the air. ... I landed on my backpack, which saved my life."
The teenager's hiking partner was walking ahead and waiting at the trailhead, Andes said. Another person also witnessed the attack.
Park rangers and Billings County paramedics were called around 11 a.m. local time and responded immediately. The 17-year-old was flown by helicopter to a hospital in Bismarck, North Dakota, Andes said.
Andes told ABC News on Monday that this time of year -- mid-July to September -- is bison-mating season. The female bison hang out in packs, while the bulls choose mates and wait for their female partners to be ready, which often leads to bulls fighting other bulls over mates.
Ron Magill, the communications director at Zoo Miami, told ABC News male bison can be territorial.
"They tend to get aggressive toward anything they think is a threat to them, their territory or to their females. ... Male animals, especially adult male animals, are very unpredictable and very dangerous. And female animals, especially with babies are even more dangerous," Magill said.
While the rangers were tending to the injured teenager, they had to keep an eye out for other bison that were in the area, Andes said.
In its Sunday news release, park staff reminded visitors that bison are large, powerful and wild and that they can turn quickly and can easily outrun humans.
"Park regulations require that visitors stay at least 25 yards (the length of two full-sized buses) away from large animals such as bison, elk, deer and horses," the park said. "National Parks are generally safe places and many people visit every year without incident, but visitors must make themselves aware of potential hazards. National Park staff is happy to assist with trip planning and information is available at visitor centers and on individual park websites."
Last week, the National Park Service said in a release that a 9-year-old Florida girl had been injured after a bull bison ran toward her and "tossed her in the air" near Old Faithful Geyser at Yellowstone National Park.
The 9-year-old girl's specific injuries were unclear, but the park service said she'd been transferred to a medical clinic and later released.
ABC News' Jessica Zellermayer contributed to this report.