Chicago Night Club

You have probably heard about the 21 people killed in a Chicago night club early this morning.

I was listening to the BBC talk about the incident and they had an interesting point. If something like this can happen when a relatively benign substance like pepper spray is detected, what happens in a large public place if terrorists release, or even make people believe that they have released, chemical or biological weapons? What if a green cloud starts to appear in Union Station at rush hour with shoulder to shoulder people. Probably something similar.