Editor's note: This updates with additional details of the attack.

A 57-year-old man hiking with his wife near the Canyon area in Yellowstone National Park was mauled to death Wednesday by a sow grizzly, becoming the first person killed by a grizzly in the park since 1986, park officials said Wednesday.

The wife also was attacked by the bear, but did not seek medical attention, park spokesman Al Nash said Wednesday night.

The victim, whose identity and hometown were being withheld pending notification of the rest of his family, was walking Wednesday morning with his wife on the Wapiti Lake Trail south of Canyon Village.

The couple had traveled about a mile-and-a-half on the trail when they spotted a bear, Mr. Nash said. The park spokesman had no details on how far the couple was from the bear, or whether the bear noticed them, but said that after seeing the bear they kept walking down the trail.

"The next time they saw the bear, it was coming at them," said Mr. Nash. "The husband told his wife to run, and she did not witness the attack."

At some point the bear came after the woman, he continued. She fell to the ground, and when the bear reached her it grabbed her daypack and lifted both the pack and the woman off the ground before dropping her and leaving the area, said Mr. Nash.

It was not immediately known if the couple was carrying bear spray, he said.

Another group of hikers heard the woman's calls for help, and they used a cellphone to call park rangers. The man was dead by the time rangers reached him, the park spokesman said.

“It is extremely unfortunate that this couple’s trip into the Yellowstone backcountry has ended in tragedy,” Yellowstone Superintendent Dan Wenk said Wednesday.  “Our heart goes out to the family and friends of the victim as they work to cope with their loss.”

There were no immediate plans to go after the bear, said Mr. Nash.

"Every indication is this was a defensive attack on the part of the bear," he said. "We're not looking for the bear, we're not planning to trap it, we're not planning to take any action against the bear."

The last fatal bear attack in Yellowstone occurred in October 1986 when a 38-year-old photographer, William Tesinsky, was photographing a grizzly in the Otter Creek area of the Hayden Valley when the bear charged him, mauled him, and partially consumed him. Previous to that killing, a Swiss woman was killed in July 1984 by a grizzly that pulled her out of her tent at a backcountry campsite in the middle of the night.

After Wednesday's incident, rangers worked to "clear the area of all backcountry users.  All trails and backcountry campsites in the area have been closed until further notice." Additionally, the South Rim Drive along the Grand Canyon of the Yellowstone also was closed Wednesday, although Mr. Nash expected it to reopen Thursday.

A bear warning sign was posted at the Wapiti Lake trailhead, "since it is one of the access points to the Pelican Valley area, known for significant bear activity. However, there had been no reports of bear encounters along or near the Wapiti Lake trail this season," a park release said. "There had been no recent reports of animal carcasses along or near the trail."

Park visitors were advised to stay on designated trails, hike in groups of three or more people, and to be alert for bears and make noise in blind spots.  Bear pepper spray has been highly successful at stopping aggressive behavior in bears, park officials said.

Hikers and backcountry users also were encouraged to check with staff at park visitor centers or backcountry offices for updated information before planning any trips in the Canyon area.  Updated information is also available by calling 307-344-2160 during normal business hours.

Despite the large number of visitors who travel to Yellowstone each year, and the hundreds of bears in the region, there are relatively few bear-human incidents, said Mr. Nash. During the past 30 years there has been less than one injury per 1 million visitors to Yellowstone, while back in the 1930s there were roughly 175 injuries per 1 million visitors, he said.