A lot of this comes from the old 1998 "Rules" started by Firearms Tactical....
http://www.firearmstactical.com/index.htm
see rule 3 for concealed carry.
As most have said it depends on the circumstances and running away may only get you shot in the back if you can't "run away". If in a parking lot it might be best to "hide" behind a car first. Just my opinions like everybodys. Who know what might happen??
og....hoping it never happens!