Yea he magically 1 shots them, insta-death, no movement. Hell COD is more realistic. If there was a shooter active why the fuck wouldn't you break a window, wait just around the corner and mass jump his ass and take him down? Something!
FFS they all went to each corner like a flock of lost sheep. Hell animals run when they hear a gunshot, they don't pretend to be a tree and stand there silently.
Goes in with mags of blanks (jams on him more as blanks tend to do that), actors act, he goes back out a couple minutes, flip flopping mags, more than enough time to smoosh some blood packs around the bodies, or hell swap the people out for dummies. Swaps to live rounds, and away he goes.