Our hyper focused, gun biased, solutions to the mass shooting problem is assuring that we will deal with this problem for a very long time. That’s a scary thing to deal with but its real. It leaves the average person with very clear choices. My experience with the modern human and clear choices is that they can paralyze people. The 21st century human would prefer to exist in an ether of pleasure rather than a world of simple choices. Your two choices are to learn to survive these mass shootings or to go on and pray you never face the barrel of a gun.
This is an article that will help you understand where to start with training and what you need to be prepared for this journey. You really need start preparing for how to react when things like this happen. Unless you plan on being a victim.