As nice as it would be to have a reliable nonlethal alternative to firearms, there simply are no nonlethal weapons capable of stopping someone who is presenting an immediate threat. Tranquilizers and anesthesia are administered by an anesthesiologist, a doctor trained to determine a dosage based on a person's body mass. Too much of a dose, or even administering it too quickly can cause serious complications, or even death. Even under the controlled environment of an operating room 1/20 patients die under full anesthesia a year.

Sadly, the most reliable method of stopping a person presenting a threat is with a firearm.

Could you clarify what you mean by 1/20 patients dying? I looked at http://patient.info/health/anaesthesia-death-or-brain-damage and it said the risk of death (England and Wales) was 1/100,000 full anesthetics.

Definitely questioning that 1/20 figure, I had full anesthesia with a surgery earlier this year and I'm pretty sure I'd be informed of that kind of risk.

For reference, what happens when you use "knock out gas" in a contained space:

https://en.m.wikipedia.org/wiki/Moscow_theater_hostage_crisi...

...everyone's reliably incapacitated, and most people survive? (potentially everyone with adequate medical care which was not provided in that situation)

That seems strictly better than shooting to kill.

130 out of 850 people died. That's a 1 in 6 casualty rate - about what you'd get playing Russian roulette.

I mean nukes are reliable too. Doesn't mean they should be used. The culture of lethal force means innocent people die.

"Sleeping gas" isn't safe. Look up the Moscow theater hostage crisis.

A dose enough to knock out an adult might easily kill a child.