About a minute after I shot this photo, a crowd swelled around the police officers in the middle of the block. Then we heard a girl screaming and saw about a dozen teens, mostly girls, chasing one girl in our direction on the sidewalk on the right. The group caught up with the girl and attacked her savagely for about 30 seconds before she escaped across the street and into a building. Lots of shouts of holy shit on the el platform where we were taking in the scene. The police missed all of it. They were too busy with whatever it was that was happening further down the street.
Update, Part II of this story.