There seems to be a bit of discrepancy over the good guy.  He and others say he came from across the street and confronted the shooter in front of the church as he left the building.  He is still a hero in my book.  However he never fired a round inside the church. That is a critical fact that changes the stories and illustrates how confused those inside the church were while this happened.
To me the good guy shows the need for those who would intervene needing to know what they are doing.  Too many posters want to believe that just packing without experience or training is all they have to do.