Does anybody else think Obama...

[Elbow]

As I mentioned earlier, location and situation determines which tool is best of the job. In your situation of 5 people above, the size of the room and placement of the individuals, along with their skills levels, as welll as your own skill level, would determine which is a better tool for that task.
A 10x10 room, with them spread out evenly all around, and you charging into the middle, does not mean you want a gun. Actually, if you have any combat skill, you would be more inclinded to choose a good long blade instead.
A gynasium or large lunch room (more in line with the Columbine situation), would call for a gun more.
Guns have a longer reach, but in tight quarters, then the knife has the advantage, due to its flexibility in use.

You have to use the right tool for the right situation. And to be clear, guns do have more situations where they are the better tool to use, but a blanket statement is not correct.
Your note of getting sick people off the streets is the part of a real approach to the problem. Planning for the worst involves placing armed individuals at schools to protect the students. The issue with that is it costs a LOT of money, and there is not a lot of extra money these days.

Let me make this clear to everyone. There is no problem with gun-free zones IF you address them correctly. Our courts are gun-free zones, yet we have armed baliffs to protect innocent people. Our planes are gun-free zones, yet we have sky marshalls. If you want to have a gun-free zone, then you have to provide adequate security for that venue. It's that simple. If you do not provide armed security on-site, then it should not be a gun-free zone.

Fixed.
A knife is better for a surprise murder in close proximity.
A gun is better to reach out and touch someone from a distance, but it is noisy and attracts more attention.

Out of curiosity, have you shot targets over 100 yards? How did you do? For most, it's not as easy as they think it is.
The longer the distance, the more practice it takes.

You're thinking about this with too much thought. I walk in a classroom full of kids, a gun will work far better. If I walked in a room with one guy, talk all the sneak attack stuff you want, I'd rather shoot and not get my hands dirty. But we're not James Bond and we're not sneaking up behind people for "silent kills" either. lol

Gun free zones can work, sure, some schools DO have armed security, others simply have security in the form of cameras, locking doors, etc. Sadly those can't protect people ALL the time.

We need to focus on the problem at hand, which is simply violent crimes in general and not mass shootings at schools, if we only focus on that we lead to the political issues and crying citizens we have right now making irrational decisions because something horrible happened. It's rare though, we shouldn't change laws on a worst fear scenario but make laws/changes that help everything as a whole.