It’s interesting to speculate what would’ve happened if someone in the theater was carrying. First, i would have to think it would be hard in the dark, especially with all the panic and commotion going on, to identify the gunman. The gunman is just shooting at random more or less, so identifying the right target is of no concern to him. Nor is he concerned what will happen if he misses his target (i.e., that he might hit someone he wasn’t aiming at). Plus, reports are that the gunman was wearing a bulletproof vest. So it might have taken a head shot to stop him, which wouldn’t be easy in the dark.
And then too, when the police arrive will they think the guy who happened to be carrying when all this went done was an accomplice instead of someone trying to take out the madman? In this case it would be obvious, at least afterward, since he wouldn’t be sporting a bulletproof vest. But would the police arriving on the scene shoot first and sort everything out later?
The cops were there in minutes ... when seconds count.
The fact remains—allowing trained citizens to carry guns will decrease gun violence.
Israel allows citizens to carry weapons for a very simple reason: because they know what works.