It did happen to fast, I believe all within 90 seconds. For the first 30 seconds you’ll be covering behind your seat just trying to figure out whats going, crying from tear gas and blind from smoke and and maybe getting ready to pull the gun out, just to be blasted after you hit his body armor when the screen is lighting up the seats quite well.
Your examples of internet cafe and brazzilian robbery would be a useful counter argument if it happened in the dark, with a crowd of over 100 panicking people and attacker was strapped to the teeth and bullet proof, while the hero gunman managed to sneak a hero headshot while being pepper sprayed or the equivalent.
Even if Holywood put Rambo into that scene and pulled the shot off, you’d look at the screen and go “yeah right, fucking Holywood”.