No, they were there because they were told.
Come on. Think about it. Not all congressmen hold town halls. So, why would all these people, all at once, start demanding the same town hall and cause the same ruckus, then create a show hall against congressmen who refused? You cannot tell me this was not orchestrated.
As for how? Well, most small towns have a public school with lots of unionized teachers. There's your base to make it look organic. The teachers' unions are the middleman. Someone is giving them orders.
(Could it be Soros? Maybe, but it could just as soon be any number of left-wing string pullers.)