I just wanted to keep you informed. You seem to think the ar-15 is an "assault" rifle, when it's nothing of the sort. Also, there's tons of smaller, more accurate, and less recoil even though the Tavor is a shorter 17 inch barreled in 9mm compared to the smaller lr22 caliber of the ar-15. That's why I think all those shooters are Manchurian Candidates, because a 5 minute Google search reveals options way better than the ar-15.
Also you can find tons of information on how to do a tactical operation, such as the correct stance, carrying an extra conscealed carry size pistol as cover while reloading, etc. Yet none of that has been done by any mass shooter. In this age of information, I find that quite strange.