A schoolgirl thug with blonde pigtails has been locked up for eight months in a youth detention centre for attacking a teenage drug dealer who allegedly sold her poor-quality cannabis "dust".
Shot on a mobile phone, a disturbing film showed the unnamed girl in school uniform throwing a series of punches at a young man's head.
This morning at South London Magistrates Court, the girl wept and hugged her parents as she was taken away.
Punches: The video has been viewed more than two million times
The girl, dressed in tracksuit bottoms and a grey top in court today, pleaded guilty of assault by beating on Saturday after the viral footage led to her arrest.
Magistrate Ken Ashken told her: "This was an extremely unpleasant assault on a vulnerable 14-year-old who did not seek to respond in any way.
"In these circumstances, despite your young age and the undoubtedly good sides that you have within you, we consider that the offence is so serious, in regards to your previous offending, that a custodial sentence is justifiable."
She was sentenced to an eight-month detention and training order for breaching a youth rehabilitation order, imposed on March 8 for grievous bodily harm and witness intimidation, plus four months for the assault.
It emerged in court the girl, from New Addington, had been under a 12-month youth rehabilitation order, imposed for grievous bodily harm and witness intimidation, at the time of the attack.
In the video, in which we have masked the identity of both the youngsters, the girl can be heard telling friends: "I'm gonna smack this yute."
This harrowing footage has already been viewed more than 2.7 million times and is being widely shared on social media.
Prosecutor Nicholas Earl-Quarcoo played the footage in court for magistrates.
Assault: The schoolgirl thug has been sentenced to eight months
"Are you gonna cry?" the female thug shouts at her victim, who does not respond to the verbal and physical attacks throughout the video.
"You need to learn not to f*** with big people. I don't let pussy boys like you violate me.
"I will have you on the floor, you understand?"
The schoolgirl thug's friends then remind her she's on camera and warn she is "stupid" to risk "ending up in jail".
But she tells them to "move away", before throwing a series of punches.
"Oooh. That one connected," says one of the girls filming the incident on a smartphone.
Shocking: Beneath the video, viewers appeared to support the violent actions of the girl
The video ends with a chilling warning to the wannabe dealer.
"Fix up, sort yourself out and when anyone on this estate comes for a draw [a small amount of cannabis], you're not giving them dust," the girl vigilante yells.
"If you're shotting [drug dealing], you're shotting properly.
"Otherwise I'm getting my youngg's [gangsters] to come and juke [stab] you."
In mitigation, the girl's barrister Kathryn Hovington said she was undergoing anger management training as part of her rehabilitation order.
She added: "[She] is a person who has shown real intelligence and insight. She is able to reflect and she knows that she becomes wound up and is unable to restrain herself.
"She regrets her actions and was not aware of the victim's vulnerability. She has asked me to apologise on her behalf. "
The girl, an aspiring beautician, remained tearful throughout the hearing and was too upset to speak when asked by magistrates.
Her barrister asked the judges to spare her a custodial sentence and instead give her an "intensive" community order.
But a representative of Croydon's youth offending team said she did not believe the girl, who cannot be identified because of her age, would comply with such an order.
Speaking outside court, the schoolgirl's father said he was "gutted".