You are so wrong in so many ways, but I'll see if I can school you a little.  Fact: There is no way to get inside someone's mind and control them.  You don't know this?  Fact: There is also no way to keep weapons away from criminals.  
Fact: Based on the article there is no way to tell who did the shooting.  Fact: There were THREE perps involved in this crime. Fact: A certain percentage of the population is just evil.  Some say 5%.

Some of us live in the real world and know that not everything can be solved or prevented.