As Tam points out you should always be sure of your target:
BILLINGS, Mont. — A hunter attacked by a wounded grizzly in a Montana forest was killed not by the bear, but by a gunshot fired by a companion trying to save him, authorities said Friday.
[…]
The shot was fired by 20-year-old Ty Bell, also of Winnemucca, as he attempted to stop the bear’s attack. No charges are expected, Bowe said.
Although I commend Mr. Bell for putting in the effort to try to save his friend I must say, ultimately, the outcome ended up being the same. Actually scratch that, there is a chance his friend would have survived the grizzly’s attack.
With that said if I’m ever being mauled by a grizzly feel free to step in and help, I’ll not ridicule you regardless of the outcome. I take that back, I’ll ridicule the shit out of you if I die.