"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."
The "well regulated militia" part of this amendment has not been instituted and no gun control laws are going to stop these type of killings.
The individuals committing these acts have serious mental issues. The mental health system was dismantled in the 1980s and treatment is not readily available. The responsibility for their care and treatment is now left to family or law enforcement. They are often homeless or end up in prison and get no treatment.
We need to invest in the mental health system and extensive training to stop this violence, not gun control.