How to get a better control of security among the US's citizens.

Hello, Mr. Obama, I am concerned about the situation of security among the schools, public areas and other places. Mainly because of fire weapons, sice almost everybody can buy one. As is known, in recent years there have been several incidents that end with a significant number of victims for a person with psychological problems or just unconscious. We as humans can be severely affected by problems in childhood. Sometimes, when a person is psychologically damaged, that person can keep its nastiness and transform it into revenge. The problem of one person comes to harm many more, why? because this person could get a firearm simply because it has the age of majority but their purposes, who monitors them? Absolutely no one and that is the problem. Take up the matter and make the change.