ANCHORAGE, Alaska — A hiker in Alaska's Denali National Park photographed a grizzly bear for at least eight minutes before the bear mauled and killed him in the first fatal attack in the park's history, officials said Saturday.

Investigators have recovered the camera and looked at the photographs, which show the bear grazing and not acting aggressively before the attack, Denali Park Superintendent Paul Anderson said.

The hiker was backpacking alone along the Toklat River on Friday afternoon when he came within 50 yards of the bear, far closer than the quarter-mile of separation required by park rules, officials said.

"They show the bear grazing in the willows, not acting aggressive in any form or manner during that period of time," Anderson said.

Investigators have identified the man but won't release his name until they've notified his family. They said he's a U.S. citizen but declined to release any other information about him. Rangers were hoping to recover his remains later Saturday after ensuring the scene was safe. Several other bears have been seen in the area.

Officials learned of the attack after hikers stumbled upon an abandoned backpack along the river about three miles from a rest area on Friday afternoon. The hikers also spotted torn clothing and blood. They immediately hiked back and alerted staff park.

Rangers in a helicopter spotted a large male grizzly bear sitting on the hiker's remains, which they called a "food cache" in the underbrush about 100 to 150 yards from the site of the attack on Friday. A state trooper shot and killed the bear on Saturday, and investigators will examine its stomach contents and use other tests to confirm it's the animal that killed the hiker.

There's no indication that the man's death was the result of anything other than a bear attack, investigators said, adding that it's the first known fatal mauling in the park's nearly century-long history.

"Over the years, and especially since the 1970s, the park has worked very diligently to minimize the conflict between humans and wildlife in the park," Anderson said. "We have some of the most stringent human-wildlife conflict regulations in the National Park system, and I think those are largely responsible for the fact that there hasn't been a fatal attack."

Park officials said they don't believe other registered backpackers are in the immediate area. That portion of the park is closed but other wilderness areas remain open, officials said.

Prior to receiving a permit to hike in the area, all backpackers in the park receive mandatory bear awareness training that teaches them to stay at least a quarter-mile away from bears, and to slowly back away if they find themselves any closer. Investigators confirmed that the hiker had received that training.

Denali is located 240 miles north of Anchorage. It spans more than 6 million acres and is home to numerous wild animals, including bears, wolves, caribou and moose.

Earlier on HuffPost: