The couple had hiked about a mile and a half when they came across the animals. It is believed the sow was attempting to protect her cubs from what she perceived as a threat.
Other hikers called 911 when they heard the man's wife calling for help, and park rangers responded.
“He was dead at the scene,” park spokesman Al Nash told the Jackson Hole News
. “I don’t know the details on his injuries.”
He said the couple saw the bears earlier during their hike and kept on walking. The second time they saw them the sow charged.
The woman said that went the bear went after her she dropped to the ground, and the animal lifted her by her day pack, then dropped her.
The area was cleared of backcountry users, and trails and campsites were temporarily closed.
“This is a wild and natural park,” The Washington Post
quoted Diane Shober, director of the state Wyoming Travel and Tourism agency, as saying. “At the same time, the likelihood of this happening again is small.”
The Grand Teton National Park contract helicopter was called in to recover the body of the 57-year-old man.
Grand Teton Park spokeswoman Jackie Skaggs said that there has never been a fatal grizzly mauling in that park, but it could happen, as some people try to get too close to the animals to watch and photograph them.
“People think they know what those bears will tolerate and what they won’t,” she told the Jackson Hole News
. “That is simply not true. They’re wild animals. They can be unpredictable.”
It is not yet known whether attempts will be made to trap or kill the bear who killed the man.
This is the first death caused by a grizzly in Yellowstone since 1986, although there were two fatal attacks in nearby areas in 2010.
"Park visitors are 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," states a Yellowstone National Park news release
. "Bear pepper spray has been highly successful at stopping aggressive behavior in bears. It is not yet known if either individual involved in this attack was carrying bear pepper spray."