People don't die if you get rid of the murderers beforehand.

Nobody puts people in Asylums anymore, they're called inpatient clinics. And plus, you can't hospitalize someone just because they show symptoms of mental illness, they have to be suicidal or court ordered to be hospitalized.

I was mainly referring to times when school shooters threaten multiple times and nobody takes any action to stop them. (Like the person from the recent florida one who had been threatening via social media for a pretty long time before he actually did it)