Philadelphia police are looking for a teenager who was caught on video knocking out a 60-year-old man. The incident started when the older man stepped on a teenager's shoe inside a train car, according to police. In the video we see the teen's friend arguing with the man—at one point a women steps in to hold him back—before the confrontation spills over onto the platform. We then see him punch the man without physical provocation, apparently knocking him unconscious.
[via Philly.com]