An investigation was continuing Saturday into the death of a hiker whose body was found in the backcountry of Yellowstone National Park.

The man's body was spotted Friday afternoon along the Mary Mountain Trail by two other hikers, who quickly left the area.

"They didn't get that close. They saw what they thought was a body, didn't want to get close, and quickly left the area and reported it," Yellowstone spokesman Al Nash said Saturday. "This continues to unfold. There's more we don't know than what we do know."

The identity of the victim, a male approximately 60 years of age from Michigan’s Upper Peninsula, was being withheld pending notification of family members.

The man apparently died earlier in the week, possibly Wednesday or Thursday, according to Mr. Nash. Citing the ongoing investigation, he could not say whether there were any obvious signs of trauma or attack by an animal. While there were signs of grizzly bear activity at the scene, he said, an aerial search of the area Saturday morning failed to turn up any current bear activity.

The Mary Mountain Trail runs 21 miles between Hayden Valley and the Lower Geyser Basin in the central section of the park. When rangers got to the scene, they found the body along the trail about 5 miles west of the Hayden Valley trailhead.

The Mary Mountain Trail, the Cygnet Lakes Trail, and the section of the Hayden Valley west of the Grand Loop Road have been closed to hikers.

Park rangers, wildlife biologists, and park management are continuing the investigation and discussing management options as more details emerge.

Park visitors are advised to stay on designated trails, hike in groups of three or more people, be alert for bears, make noise, carry bear pepper spray, and not to run upon encountering a bear.

Hikers and backcountry users are encouraged to check with staff at park visitor centers or backcountry offices for updated information before planning any trips in the central portion of the park.