The hikers were injured May 4 on a trail near Old Faithful, according to the National Park Service.
YELLOWSTONE NATIONAL PARK, Wyo. — A grizzly bear that attacked two hikers in Yellowstone National Park this week was likely a female bear with cubs, according to the National Park Service.
The attack happened on Monday afternoon on the Mystic Falls Trail near Old Faithful, NPS said in a news release. It was the first incident of a bear injuring someone in the park this year.
On Thursday, the park service said that evidence collected so far indicates that the bear that injured the hikers is a mother with two or three young cubs in the first year of their life.
The park service also said on Thursday that the two hikers who were injured are both male, ages 15 and 28. After the attack, they were treated at the scene by emergency responders before being transported out by helicopter. NPS did not disclose their condition.
Trails, backcountry campsites and fishing areas northwest of Old Faithful remain closed. There are no known visitors in the closed backcountry areas, NPS said.
The bear attack is still under investigation, the park service said.
Before this attack, the last time a visitor was injured by a bear in the park was in September 2025, when a hiker suffered injuries to his chest and arm. The last human fatality caused by a bear occurred in 2015, when a 63-year-old man was killed while walking along near the Lake Village area.
After the deadly attack in 2015, officials captured and killed an adult female grizzly because it had eaten part of the victim’s body and hid the rest, which is not normal behavior for a bear defending its young.
The Associated Press contributed to this report.