Yellowstone National Park officials on Thursday identified the victim of a grizzly bear attack as a 57-year-old Torrence, California, man, and adjusted some of the details of the attack.

Brian Matayoshi was killed in Wednesday morning's attack, while his wife, Marylyn, was briefly picked up by the bear but did not require medical attention, park officials said. The attack occurred about 11 a.m. as the couple was hiking along the Wapiti Lake Trail, which is located off the South Rim Drive south of Canyon Village and east of the park’s Grand Loop Road.

The couple was returning to the trailhead toward their vehicle when, about a mile-and-a-half from the trailhead, came out of the lodgepole pine forest and into a meadow, a park briefing of the incident said.

"It appears that the couple spotted a bear approximately 100 yards away and then began walking away from the bear.  When they turned around to look, they reportedly saw the female grizzly running down the trail at them," the release said. "The couple began running, but the bear caught up with them, attacking Mr. Matayoshi. The bear then went over to Mrs. Matayoshi, who had fallen to the ground nearby. The bear bit her daypack, lifting her from the ground and then dropping her. She remained still and the bear left the area.

"Mrs. Matayoshi then walked back toward the meadow and attempted, without success, to call 911 on her cell phone. She began to shout for help and was heard by a distant group of hikers who were able to contact 911 by cell phone. Two rangers already in the area on backcountry patrol were contacted by the park Communications Center by radio and responded to the scene of the incident."

Mr. Matayoshi had died from "multiple bite and clawing injuries" by the time rangers arrived at the scene at approximately 11:30 a.m., the park statement said. The couple was not carrying any pepper spray, according to park officials.

Rangers immediately closed hiking trails in the area, and a helicopter patrol was used to determine whether there were any other hikers already in the backcountry in that area. None were spotted, and park officials closed the area for the coming days.

"The initial investigation suggests the sow grizzly acted in a purely defensive nature to protect her cubs," the statement said. "This female bear is not tagged or collared, and does not apparently have a history of aggression or human interaction.  Typically, the National Park Service does not trap, relocate, or kill a bear under those circumstances.  A Board of Review, which will include interagency experts, will be convened to review the incident."

The last fatal bear attack in Yellowstone occurred in October 1986 when a 38-year-old photographer, William Tesinsky, was attacked while "stalking" a grizzly in the Otter Creek area of the Hayden Valley, according to park officials who investigated the incident. The Montana man got too close to his subject, former Yellowstone Chief Ranger Dan Sholly wrote in his memoirs from the park, recounting that "before he could even press the shutter release" to snap a shot the bear charged him, mauled him, and partially consumed him.

Previous to that incident, a Swedish woman, Brigitta Fredenhagen, 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. Rangers had warned her about hiking alone in the backcountry, according to Mr. Sholly's account in Guardians of Yellowstone, An Intimate Look at the Challenges of Protecting America's Foremost Wilderness Park.

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.