I have run into plenty of gun carrying people who, like me, mentally roll play different defensive scenarios that they may wander into from time to time. I have found that in many of these scenarios, it usually entails several aggressive males approaching or whatnot, kind of like a "Yo homie! Is that my briefcase?!" kind of attack. Unfotunately it doesn't always end up being such an easy choice on if/when/how to intervene to protect yourself or someone else.
Here is a video from Liveleak that was posted on Drudge and ARFCOM showing a brutal attack by two women on another girl in a McDonald's, rumored to be in Baltimore. I will warn you that this video is very disturbing:
Now gauge what your response would be if you were a patron at this resaurant. This attack went from a moment or two of fisticuffs to flat out head stomping, and if you have the stomach to watch til the end, there's blood and a seizure in there as well.
I show this as an example that an attacker(s) may not always be large aggressive males that present you with the time to react. This could be your wife or significant other being attacked by two women, and you walk out of the restroom and have to make an immediate decision on what to do. If the victim was a complete stranger to you, what would you do?
Discussion here at ARFCOM.