WYOMING — Two hikers were attacked by one or more bears on the Mystic Falls Trail near the Old Faithful geyser at Yellowstone National Park on Monday afternoon. Emergency personnel responded to the scene, and the incident is under investigation.

Park officials did not reveal the extent of the hikers' injuries. At least five trails and multiple campsites at Yellowstone were closed following the attack.

The encounter marked the first time this year that a bear has injured people inside the park. The most recent bear attack in Yellowstone before Monday occurred in September, when a 29-year-old hiker was seriously injured in a surprise encounter with a bear on the Turbid Lake Trail.

The last human fatality caused by a bear inside Yellowstone occurred in 2015. In 2023, a grizzly bear killed a woman just west of the park.

Park officials reminded visitors to stay at least 100 yards away from bears, carry bear spray and look for possible signs of the animals. Guidance issued by the park urged hikers to "See the bear before you surprise it." and to "Watch for fresh tracks, scat, and feeding sites."

Scientists spotted the first grizzly bear of 2026 at Yellowstone in March, indicating that hibernation season was ending for the animals. More than 1,000 grizzly bears live across the greater Yellowstone ecosystem, which covers parts of Montana, Idaho and Wyoming outside the immediate park boundaries.

Grizzly bears are listed as threatened under the Endangered Species Act. The species was brought back from the brink of extinction in the contiguous United States over the last five decades. Yellowstone officials estimated that the grizzly bear population in the region had dropped to just 136 in 1975. The population currently occupies more than 27,000 square miles and is expanding its habitat.