Yep, been discussing it all day on a Texas firearms forum I'm on. There's been a lot of arm chair experts criticizing the reaction time of those involved, but honestly I felt they did an excellent job given how quickly it happened. It appears the defender made a 20-22 yard head shot. God bless him!
Certainly the fact that a lot less than the 26 killed/20 wounded from Sutherland Springs and the state easing up on the restrictions where licensed individuals can carry proved that such tragedies can be avoided or minimized when armed, law-abiding citizens are present.
It's sad that people have to protect themselves from such threats, but the reality is failing to do so can have much more terrible consequences.