A good guy with a gun halts church massacre., page-3

Yes, "this guy was a professional" & not just an armed parishioner.

"The armed man who fired back at the would-be mass murderer has been identified by church members as a former FBI agent and a designated security guard for the congregation."

https://conservativeangle.com/breaking-church-shooting-reported-in-texas-suspect-shot-dead-by-armed-good-guy/Also

Further;

"An elder at the church told the New York Times one of those killed was a security guard who responded to the shooter."

https://www.abc.net.au/news/2019-12-30/texas-church-shooting-gunman-shot-dead-by-parishioners/11831990

(Who is the bloke in the photo?)