When has ANY mass shooter been conforming to the laws that already exist?
Passing new ordinances to “prevent” these mass shootings is a totally ineffectual response, and in fact, makes the next assault of unarmed people in confined spaces all the more likely.
The risk to the perpetrator, before he accomplishes his objective (and it is almost always a male who is the perp) is actually very low, and the chances of detection before opening fire are equally low. But if there is any apprehension that that the crowd at which he may direct his fire has any members that are armed and well able to shoot back, the risk factor for the perp is vastly increased.
Not a perfect solution (locking up or otherwise controlling the actions of all the unstable persons would be a much better one), but this is not a perfect world.
Archie Bunker solution to prevent hijackers on planes - issue all the passengers a loaded sidearm when they board, then when a hijacker tries to get bold, he will have several dozen sights trained upon him. Makes people much more polite.
McVeigh was the last mass murderer thatthe feds have put to death, that alone speaks volumes about the perverted INJUSTICE system in this country.