Philadelphia Mayor Michael Nutter and other city leaders say they won't tolerate a deadly "knockout game" in their city in which teens approach strangers and try to knock them out with just one punch.
The attacks have happened in several states and in England, and have resulted in at least two deaths.
Reports suggest some of the attacks are racially motivated. Surveillance video shows one Pittsburgh victim getting knocked unconscious last year.
"It's disturbing, it's frightening," victim Jim Addlespurger said about his experience. "It's a terrible thing, I'm not comfortable looking at it."
A "knockout" victim from Brooklyn, 62-year-old Lauro Ponce suffered a traumatic brain injury after his attackers sucker-punched him in the face and fractured his skull. Now he is in a nursing home.
"This was one punch. Innocent man walking down the street, minding his own business and his life has changed forever. And it's never going to go back to what it used to be," his niece Johanna Ponce shared.
Nutter said that anyone caught participating in the attacks will face a minimal charge of aggravated assault. He also indicated "game" players could face serious charges of third degree murder if caught.
His warning is the latest example of political leaders and law enforcement who are fighting back against the deadly attacks.
"You're also hurting another human being for no reason at all. There's no excuse for this kind of behavior, it will not be tolerated here in the city," Nutter said.
"We will do everything we can to both prevent, but if someone does engage, we will catch you. You'll be prosecuted and your life will be changed dramatically," he said.
It's hard to confirm, but numerous reports indicate victims have been attacked for their race or religion. In one case in New York, police have charged assailants with a hate crime for targeting an orthodox Jew.