Of course the people that shoot other people in a grand spectacle are mentally deficient.
Require all owners and would be owners of firearms to have a license stating they are mentally competent to own and operate firearms. Like other licenses it would require yearly renewal and a full-on psychological exam so that the government can't use that as an excuse to illegally take our guns away.
As a reminder and as stated in the Second Amendment to the U.S. Constitution: "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed"
Start enforcing the existing laws concerning gun crimes and stop brain washing the people into thinking guns are the problem.