A hunter was killed in a grizzly attack in Alberta a short time ago. Poor guy ran afoul of a sow with a cub and a kill cached nearby. I suppose hunters are more at risk because they are trying to move quietly (as opposed to hikers making noise deliberately). Don't know if he had time to fire a shot, but if a mad griz comes out of dense bush at full speed you're a pretty amazing (or lucky) marksman if you can make a lethal shot in that situation.

http://news.nationalpost.com/2014/09/09/...ly-bear-attack/