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.