Words fail me. (Well, no, obviously they don't, but I love saying that.)
Quite apart from the possibility of a response from armed theater patrons, to pull a stunt like that in the wake of Aurora and
Boston is just... insane. ONE person has a heart attack, and the result could have been tragic without a single shot being fired.
According to this article
in the Hollywood Reporter, police did respond, thinking it was an active shooter situation. If fake 911 calls are illegal, something like this ought to be, as well.