A Yellowstone National Park hiker whose body was found mauled last week was killed by a grizzly bear, authorities reported Monday, the second fatal bear attack in the park this summer.

The hiker was identified as 59-year-old John Wallace, a Michigan resident who was traveling alone and had pitched his tent in a campground along the Mary Mountain trail last Wednesday. Wallace's body was discovered on Friday by two hikers in an area of the park that was closed to hikers, according to park services.

Rangers discovered signs of grizzly bear activity, including tracks and bear droppings, in the campground where they believe Wallace pitched his tent.

There was no witness to this incident and we really don't have a lot of information to help us determine why this attack may have occurred, Al Nash, a park spokesman, told The Los Angeles Times.

An autopsy concluded that Wallace died from traumatic injuries he sustained from the mauling. Nash said park rangers are conducting fly-overs of the area where the incident took place to see if they can locate the bear involved in the attack.

Wallace is the second Yellowstone visitor to die of a bear attack this summer. In July, a female bear attacked and killed a 57-year-old man, which park managers determined occurred because the bear was attempting to protect her cubs.

Although the attacks occurred in similar areas, officials do not believe the same bear was responsible for Wallace's attack since no evidence of cubs were found on the scene.

However, DNA tests will reportedly be performed on hair samples from both scenes to confirm that a different bear caused the second fatality.

Despite the repeated attacks this summer, park officials report that no human had been killed in the park since 1986 prior to this year. In recent years, Nash said there has been one bear-related injury for every 3 million visitors to the park.

The number of grizzly bears in the American West has plummeted to about 1,500, according to the Natural Resources Defense Council, which reports 100,000 once roamed the area in the early 1800s. The National Park Service reports there are between 280 and 610 grizzlies left in the Yellowstone ecosystem.

Visitors to Yellowstone are advised to stay on designated trails, hike in groups of three and more, and carry bear repellant spray to reduce the chances of having an unexpected encounter with a grizzly bear.