The 27th mass shooting this year, I think. Last year there were 44. I don't think this is what the founding fathers had in mind with the Second Amendment.
Please, please, this is not an attack on you, it is an academic answer to your question. What the founding fathers had in mind is for the individual, and the group, to be able to protect themselves. In their day, troops would march up to the village and tell people "We are taking 50% of what you have, what you have worked hard and long to earn and save and there is absolutely nothing you can do to stop us."
Fed up with that, on April 19, 1775, the colonists gathered in Concord and on the commons of Lexington Green and stood their ground, against, what was then the mightiest and most powerful country on Earth.
21st century revisionists would say "Yeah, but the colonists didn't have assault weapons." Actually, the colonists had weapons that were the same quality as what the military had. The Founding Fathers felt that government should fear the people, not the other way around.
Colonists also believed that gun owners should be responsible. What the Founding Fathers didn't foresee was ultra violent video games. Kids get so desensitivized because night after night they kill hundreds of zombies, aliens, or whatever. So, because kids get desensitivized, the best response is just to have, at least, one armed guard, per school. Unfortunately, seeing an armed guard makes teachers queasy, so to prevent teachers from getting their feelings hurt, armed guards aren't allowed in school.