The police are outnumbered.
They walk in, knowing nothing about how the crowd was riled up or who is responsible.
All they know is who the crowd is following.
It's standard practice to arrest the "leader" and break up the crowd.
Given their responsibilities and desire to prevent violence, that was probably their only option.
Next time, someone needs to greet the cops and fill them in on what's happening, offer to take the microphone and calm things down, etc.
This is all about fear--the cops were more scared than anyone else in the room.
What do you think? http://consequeries.com/