It is not a matter of fault, it is a matter of tradeoffs.

If people have the freedom to own guns, and events like this are the cost, is it really worth it?

Other countries don't have the same permissive gun laws, but they also don't have dozens of shootings every year. They don't have children that bleed to death in their classrooms, watch their friends die, or have drills in case they are ever confronted with those situations.

Are they worse off because they can't walk into Walmart and buy a gun, or are they better off because their kids don't live with the risk of being slaughtered?

You tell me.

These killings are a CIA Operative. Taking guns from law abiding citizens has nothing to do with this. You're responding exactly how they want you too. Tell me how a messed up transgender kid living with grandma got a hold of weapons worth at least $5000?