I struggle with this issue as a libertarian as I believe strongly in the rule of the individual and personal responsibility, but these horrible killings truly wound my soul. When I remove the emotion from the equation I understand that removing guns doesn't end the violence. People don't kill because a weapon is available people create weapons to kill, the weapon is merely the tool.
I would like to see more effort put into early detection of mental disorders and stricter laws on who can purchase a firearm,although the latter will have little effect. I also think requiring storing AR at public armory's and shooting ranges, would be a reasonable restriction.
But I keep coming back to mental health and quite frankly parenting. I know relatives that allow their 5 year olds to play violent shooters and it shocks me as a parent. I would never allow a child of any age play these games, we try to justify it by saying it doesn't affect them but I think we are only kidding ourselves. The responsibilities of the parent and frankly the responsibility of the government to allow parents to act against their children they know may need to be institutionalized is very important.