A Montana man was found dead in Yellowstone National Park on Friday and authorities are investigating whether a grizzly bear might have been responsible.

“Although there were signs of grizzly bear activity in the area, a conclusive cause of death, which likely occurred on Thursday afternoon or Friday morning, has yet to be determined,” Yellowstone officials said in a Friday evening news release.

Co-workers had reported the man missing on Friday morning. A park ranger found the hiker's body around noon in the vicinity of the Elephant Back Mountain loop trail, which is near the Lake Village area, the news release said.

Park officials did not release the man's name on Friday evening because his family members had not yet been notified.

“Hikers are advised to stay on designated trails, leave an itinerary with others, hike in groups of three or more people, be alert for bears, make noise, and carry bear spray,” the park said in its news release.

The Elephant Back Loop Trail and immediate area is closed to hikers while the investigation continues.

The 3.5 mile trail starts not far from Lake Village, heading roughly north from the Grand Loop Road and winding through a dense forest to reach a scenic overlook of Yellowstone Lake and the surrounding area.