Hunt for black teens seen in horrifying video sucker punching mentally challenged man

A mentally challenged man was sucker punched in the face as he walked down a street in the Germantown area of Philadelphia.
In a 30-second video which was recorded in slow-motion, a man is seen smiling before being distracted by a teenage boy who punches him hard in the face for now apparent reason and without warning.
The victim appeared to be in complete shock by the attack and was knocked backwards by the impact.
As the man attempts to walk away, he is then pounced upon by a second older man who punches him in the ear while another laughs hysterically at the beating.
All the men are clearly visible in the video but police do not yet know their identities and are hoping members of the public will come forward to help name and shame them.
Gerald Andrews Sr., 48, told Philly.com that the victim was a co-worker at a ShopRite in Cheltenham and identified him by his first name, Mark.
'He keeps that smile on his face. He wants to talk sports. He's a good guy. It's heartbreaking,' Andrews said speaking about the attack that he learned about from a co-worker.
Detectives are now investigating the assault.
'Obviously, what is depicted in the video is very disturbing,' said police spokesman Sgt. Eric Gripp.
'We would implore anyone who has info on the video, or who knows the identity of the victim to reach out to police.'