Contrary to current faddish ideas, we cant identify much less imprison "potential" mass murderers. For many mass killers, mass murder is their first serious crime. Its NOT against the law to be crazy, in California and Illinois it actually makes you more viable as a candidate for public office. The best we can do is enact policies that will reduce the death toll when these acts of carnage occur, as they will in a free and open society with well over 300 million people. States that allow concealed carry handguns have reduced multiple shooting attacks by 60% and reduced death and injuries from these attacks to over 70%.
Its difficult to explain why more than 99% of people with easy access to guns dont engage in rampage killings, if the problem were the availability of guns we should all be dead.
The head of Handgun Control Inc. once recommended that women faced with a rapist or robber, simply give them what they want. They left out the part that maybe they will get shot anyway, but what the hell, actual solutions arent the goal here. The fact that guns can kill another human being is the whole point, Thats why they are so good at deterring violent criminals. Gun Free Zones are enablers for murderers. Nothing says come on in and rape the women and kill us all like a gun free zone sign.