I got in a few fights, won most, lost a couple. Never fought the same guy twice. Most times they resulted in mutual respect after the fact. I even did some bullying, much to my regret later in life.
But these kids aren't doing either of those things. They are savaging and brutalizing a defenseless person, without conscience or restraint. If he'd not have run away, it appears to me that they would have eventually killed him. He was one head-slam against the pavement; one kick to the face; one head-first tackle into the wall - away from serious injury or death.
I think these punks deserve whatever they have coming to them, and I hope its the very worst.