I've been involved, as close bystander, in a mass killing situation in 1989 when a crazy gunmen came into my university (Polytechnique), seperated men and women in a class, and shot the women (14 died).
I think that going into the face of gunfire is an unnatural act and has nothing to do with being a real man or women; 99% of human being will flee and I did too, the gunfire was one floor down, I heard in BANG, BANG, BANG.... What direction is he going... I was running right, left, we all felt like headless chicken, when we were sure he was going in one direction from the gunfire we went the opposite way, found a corner staircase and went down the stairs and out in seconds... While that was going on, I didn't think, It 1000% of adrenaline... I called my mother as soon as I had my mind back so she didn't worry while the shooter was still inside shooting.
Next day, I found out he only shot women, and I knew two of them, I did two session long projects with each of them, they were my age, young brillant women with such a future in front of them cut down by a mysoginist!!! I cried for hours.