[101stAirborneVet]

Not necessarily. Different people respond differently to different types and concentrations of irritants. I am practically immune to CN, but oleoresin capsicum puts me down. You also have to consider the amount of time it would take a dispensing canister to become effective in a large room such as a theater. There’s a window of at least several seconds in which to act.

[justa-hairyape]

From eyewitness accounts, he kicked open the emergency exit door. Threw two canisters. Then waited until they exploded. That was when he reached around and grabbed his gun. Movie goers originally thought it was part of the premier showing. When the canisters exploded, that was when they all hit the ground and knew something was wrong.

[Future Snake Eater]

Ah, you’re one of those lucky ones. That stuff puts me on my ass in a flat second.

Good point about the billowing time factor. Of course, if he didn’t start shooting until it was billowing, then that would make it that much harder to respond. Regardless, that’s not a place you’d want to be even if there wasn’t a shooter.