They also weren't closed in at the WTC. In an indoor arena, I imagine some would panic. I wouldn't, nor apparently would you, but some likely would. But you may be right.
Let's just hope we don't have to find out.
There's always someone who loses it, but most don't. However, if there is an attack like that there will be a lot of very annoyed people and several things will ratchet up both in the country and internationally.