Well, it's a bad situation no matter how you cut it. I think if I had family with me, then I would have to do whatever was best for them. So, am I or my family being fired upon, am I fixing to be fired upon? It looks to me like I would either need to be shooting, running, or crawling away, or hiding behind something.
I would say that the right training would help in making the best decision, also knowing what you can do with you carry gun, would enter into it. An accurate, and powerful carry gun would make some difference in this case. With a heavy gun, even hits on a bullet proof area might help to stop the perp long enough to get closer or make a better follow up shot, but a tiny mouse gun would not be very effective. A man's really got to know his limitations.
It has been said that most men regret the things they didn't do, more then the things they did do. One thing that I would regret is knowing that I let other people die, because I didn't have the guts to do something in my power, when I had the chance.