A 15-year-old girl was brutally beaten and robbed by a group of almost 20 teenagers after they chased her around Brooklyn, New York.

The NYPD released footage of the horrific attack which was captured by security cameras.

Authorities said the incident began around 4.10pm Thursday when the victim was approached by a group of unidentified individuals in front of 216 Utica Avenue.

It's unclear what started the altercation, but surveillance footage shows the group of young teenagers chased after the girl until she fell on the sidewalk.

Surveillance footage shows the 15-year-old girl falling on a sidewalk near Utica Avenue while being chased by a group of teenagers

Then, nearly 20 individuals jumped onto, kicked and punched her several times as the group swarmed around her.

As the suspects fled the scene, one of them stole the girl's sneakers off her feet while she's on the ground. Her phone and debit card were also stolen.

The girl was transported to NYC Health & Hospitals/Kings County to be treated for head trauma and bruises.

Authorities believe Thursday's assault could be in retaliation for a previous slight, but the details of that are unclear.

Assistant Chief Jeffrey Maddrey of NYPD Brooklyn North said the ordeal was outrageous.

Nearly 20 individuals were captured jumping, punching and kicking the 15-year-old girl Thursday afternoon

The suspects steal the girl's sneakers, debit card and phone during the violent altercation

'...This is sickening video of a 15 year old girl viciously attacked by a group of school children,' he wrote on Twitter.

'One young man takes the sneakers right off the unconscious victim’s feet. The teenager is in the hospital recovering. We CAN NOT allow this behavior in our community,' he added.

According to the NYPD CompStat 2.0, there are 2,499 robbery reports this year so far, making a 34 percent increase from 2019.

Anyone with information in regard to the identity of these individuals is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).