Just to let you know Suzanna Hupp's father tried doing that at the Luby's Massacre in Killeen, Tx
He didn't make it that far - brave but most often a last resort option. By him doing it - saved several other's lives.
http://en.wikipedia.org/wiki/Suzanna_Hupp
Everyone has to come to their own decision on what they would do.... We're all different and we'll all be faced, if at all, with different situations.