Transcript for Philadelphia Girls Charged in Videotaped Beating
This surveillance tape shows six girls on a mission at one point they -- -- warm up by wrapping. -- -- -- And they can't -- that would then yeah. Muttering obscenities or one of the girl signals they are going to harm someone that someone is a 48 year old mentally challenged woman sitting on her front step. This is cell phone video shot by one of the attackers posted on FaceBook it all starts with this -- The attack goes on for about fifty seconds but chair is -- and then it's over as quickly as it started in the sixth fleet. Detective James -- to take. Absolutely no reason for behavior like this. This is something that occurs in the city that normally we don't have. Evidence. You hear about things like this be generally don't see them this neighbor of the victim says she told him she does not want to return here to her small apartment. This young man who has often seen the victim sitting on her staff was unnerved by the attack video I was scared now. That someone could do that's another human being tonight young people who gathered near where the attack took place -- they did not recognize anyone on the video. Longtime resident Dorsey Williams says she hopes to find out it looked like somebody who knows there will be era. The question of why hangs over all of this why do it white -- -- white posted. And it's an unfortunate sign of our times. You know. Kids do things today and I have no concept. Of the consequence it's a joke they -- in the video downloads and hadn't seen.
This transcript has been automatically generated and may not be 100% accurate.