When I was 19, I attended an Iron Maiden concert in San Antonio with a friend. We were watching the band, when a security guard came over and asked to see my friend's ticket. He pulled it out and held it up for the guard to see, but didn't take his eyes off the band. He was grabbed in a headlock and dragged to the railing by the stage. The last thing I could see was my friend being literally thrown over the railing into the backstage area.
I left and met him outside. He wasn't seriously hurt, but it sucked that we had to miss a concert we paid for because a security guard got his feelings hurt.
I'm not surprised by this story at all. Happens all the time.