I just read a story about a hiker that was mauled by a grizzly in Yellowstone Nation park near bakers hole campground. He under went surgery for multiple wounds and was due for more surgery but he suffer a heat attack and did not survive. He was in possession of bear spray but it was unclear if he was able to use it. The bear was killed when it came at several rangers. they found a moose carcass a shot distance from where the bear was killed. These things will happen, just always be aware of things around you when you are in the wild.
