Hostage situations, possible strategies

Something came up as I was reading up on that bastard who went into a colorado school and killed a 16 yr old girl as she fled (shot in the back of the head, that sucks sad ). This is just all theoretical, but do you think it might work?

1.) Stun grenade thrown into area where the crook/hostages are at. The grenade will create a loud noise and flash, which will momentarily disorient anyone who's not "protected" (i.e. they're not closing their eyes and covering their ears, which is the whole point of the grenade, you do that before they can react). This would give the cops a few moments to take down the crook.

2.) Tranquilizer dart. Would require the criminal to be in good view of a good sniper, but with a good shot it would knock out the criminal quickly (or at least I hope it's quick enough before they can do something like shoot a few hostages beforehand).

3.) Sleeping gas, or something similar. Sort of like what the Russians used in that theater hostage situation a few years ago (yes, I know, it was kind of bad because some of the hostages got really sick and/or died from it, but at the same time they did kill all the criminals too. Real easy to put a bullet into their head when they're asleep), except you don't tell them, you just do it. Might be more effective if it's a long stand-off, going into the night hours and what not (sure, they might be able to stay up for a while, but I don't think any human could stay awake and alert for much longer than that).

4.) Giving in to the hostages demands if they want a car/plane/helicopter/safe transport away. Then once they're in said vehicle, do either 2 or 3 above in the vehicle. This will probably be more probable when computer controlled cars are common, and as a bonus, if the criminal is incapacitated, the car can go directly to a prison, where the hostages can be freed, and the criminal doesn't have far to go behind bars. If they're terrorists, alternate plan (especially if they don't have any hostages with them) is to let them get away, and once they're a safe distance away, blow it up (particularly if they killed other people already).

I know some of these are really far-fetched, but realistically speaking, could that stuff work? I know it calls for some really unorthodox methods, but hey, you have to try and think like the criminals, so you can try to one-up whatever they do.

And if you have any suggestions, feel free to post them (probable ones preferably, that you could probably realistically use. Much as I'd like to send a Terminator in there, I don't think they'd work well unless they could incapacitate the crook before they could harm any of the hostages. And energy shields to detain the crooks won't be in service for the forseeable future tongue Yes, I can think of stuff that's out there too lol).

Jam it back in, in the dark.