A Yellowstone national park trail remained closed on Wednesday after a possible grizzly bear attacked a hiker, leaving him with serious but non-life-threatening injuries.

The 29-year-old man suffered injuries to his chest and arm in Tuesday’s attack on the Turbid lake trail north-east of Yellowstone Lake.

The man encountered the bear 2.5 miles (4km) into the backcountry and sprayed bear repellent as it began to attack, park officials said in a statement.

National Park Service medics walked out with the hiker. He was then taken to a park clinic and flown to a nearby hospital.

Park officials said on Wednesday they had no more information including the man’s name, where he was from, and updated condition.

It was the park’s first bear attack since a grizzly injured a hiker in the Mammoth Hot Springs area in 2021. That hiker was able to hike out on his own.

A grizzly killed a woman just west of Yellowstone in 2023.

The bear in the latest attack will not be relocated or killed because it attacked during a surprise encounter and did not exhibit unnatural behavior, according to park officials.

DNA analysis could determine the species. The man believed it was a black bear but its location, size and behavior suggested it was a grizzly, according to the statement.

Grizzlies and black bears can be difficult to tell apart at times. But grizzlies grow much larger – as much as twice as big – and black bears usually have darker coloring.

Grizzlies are federally protected as a threatened species in the lower 48 US states, where their numbers have rebounded from about 700 in the 1970s to about 2,000 today.