A hiker in Yellowstone National Park is dead after an encounter with a grizzly bear Wednesday morning. Park spokesman, Al Nash, says the incident occurred on the Wapiti Lake trail. A husband and wife were hiking about a mile and a half in when they apparently surprised a grizzly sow with cubs.

"We're still trying to determine exactly what happened, but the male was fatally injured by the bear. Other hikers on the trail heard his wife's cries for help. They were able to use there cellphone to call 911 and summon park rangers."

The incident occurred in an area southeast of Canyon Village. Nash says investigators are still in the back country attempting to reconstruct what happened.

"It's important for us, as we move forward, looking at what may occur with the bear and to look at  information that will help us determine when we can reopen the area. Our first focus is on the victims of this incident and then it was about that we protect the safety of park visitors. So we've closed some trails and some back country campsites. And we sent people into the back country to help move any users out of the area."

The name and hometown of the victim are being withheld pending notification of family members.

At this time Nash says they encourage anyone with plans to visit the Canyon area to call the park during business hours to find out what areas remain closed.

This is the first bear-caused human fatality within Yellowstone since 1986.