Something along these lines happened around me recently, where a mental patient came to a hospital on slice his doctor up pretty badly, and a ccw permit holder took him down. Guy was an off duty security guard, so no real "extensive training" to speak of (no HRT or something like that). Probably saved the doctor's life and maybe some others. I guess all I'm really trying to get at is that once the BG's intentions/actions get violent, it's a different situation, and you may have to act lest your life be in immediate danger.
That being said, he was in a situation with one assailant. One on one, your odds are a lot better than one v. multiple shooters. If you happened to find yourself in a situation with more than two, or two that are well spread out, it would be a better idea not to start the shooting, unless you are in a situation where you're going to lose your weapon or your life if you don't. I definitely agree with some posters that most times you should do nothing except try to get clear of everything, but then again, you might have your back against the wall at some point. If you found yourself in the middle of a robbery or something like that, well, let the guys get the money and go-they're not your problem. A real hostage situation, though, especially in today's world, is a different ordeal altogether.
I'm definitely not saying this in any mall-ninja type of way either. I have no illusions that any of us is going to do anything on the level of FBI HRT or something from the movies. The chances of being involved in something like this are extremely low, but it's not a bad idea to spend some time thinking about it, or any other situation where you might need to defend yourself or your family, because if you're going to carry, you want to have an idea what your options might be in a given scenario, even though the hope is definitely to never be involved in anything. It's not that different from thinking about your options if someone breaks into your house-a much more likely scenario-you want to have some ideas and a loose plan in place so that if, God forbid, it happens, you're not shooting from the hip (pardon the pun). It's the same reason real HRT teams train for such a wide variety of missions, and hash out even more-if the call comes, they're not doing anything blind. Every situation is different, and most of the time your best bet is going to be hold your peace, get the heck out of there and let the pros do their job, because yours is likely not freeing hostages.
Don't forget that most hostage situations happen by mistake, the takers get boxed in in a botched criminal effort, and are looking for a way out, or a bargaining chip for a way out, not a reason to give the police more incentive to kill them, so it is likely a much better idea not to give the taker(s) a reason to hurt any hostages. If they're taking hostages for the sake of taking hostages, and you can't get out, you're in a very bad situation, and it's at your discretion how to proceed.
