A police officer has been suspended after a video emerged showing him rain punches down on the head of a 12-year-old girl.
Officers had been called to reports of a fight between two sisters, aged 12 and 14, and a 14-year-old girl.
Reports suggest he was punched by the 12-year-old girl before appearing to try and detain her.
Emergency services were called to a bus stop near a school on Staten Island, New York, US, on Tuesday at around 2.40pm.
The NYPD released a statement on Twitter saying an investigation has been launched.
It read "Last evening, the NYPD became aware of an incident that occurred on Staten Island where officers responded to a fight between a group of youths.
"The actions of those officers is under investigation by the Internal Affairs Bureau. At this time, one officer has been suspended."
In the video the officer appears to rain punches down on the back and head of the girl as others try and pull her away.
An onlooker can be heard saying: "He's hitting her? What the f**k!" A girl can be heard screaming: "Don't do that!"
The officer's name has not been released.
Both sisters were arrested with the charged with resisting arrest and assault, and the younger with a juvenile report alleging assault.
NYC council member Kamillah M. Hanks said that the girl was a student at a nearby school.
She said: "Yesterday, an incident occurred at the dismissal of I.S. 51 middle school, where a student was seen involved in an altercation with an NYPD Officer.
"I would like to thank the concerned community member who sent me the video of this incident.
"I immediately contacted NYPD to request an investigation. I am encouraged by the NYPD’s swift and appropriate response to this matter.
"Let me be clear - violence against our children is unacceptable will not be tolerated."
The video was shared widely on social media with many users expressing their shock.
One outraged Twitter user said: "That is so excessive."
Another pointed out: "The cop threw like 8-9 punches, all of them hammer fists to the back of the head.
"That's literally the most dangerous punch, illegal in every combat sports organisation."
One went even further: "Is he repeatedly punching in the back of the head? is that not attempted murder?"
The NYPD is a huge police force larger than many countries' armies.
It has a budget of $10.8 Billion (£9bn), which is more than the GDP of Tajikistan, a country with a population of 10 million.
