A video of United States police violently tackling a Black teenager during a mall fight with a young white man has sparked outrage, prompting the state's governor to condemn what appeared to be "racially disparate treatment."

The video – posted earlier this week by the platform Storyful and picked up by ABC, CBS and CNN – shows a fistfight breaking out between two teenagers at a shopping mall in Bridgewater, New Jersey, a suburb of New York city.

After about 10 seconds, two police officers arrive and forcefully separate the teens.

But while the Black teenager is violently thrown on the floor by one police officer, the young white man is simply made to sit on a sofa.

A police officer is then seen putting her knee on the back of the young Black man as he lies flat on his stomach, while the male police officer handcuffs him.

"They basically tackle me to the ground and then the one – the male officer put his knee in my back and then he starts putting me in cuffs," the Black teen, who gave his name as Kye, told ABC.

"And then the female officer came over and put her knee on my upper back too and started helping putting cuffs on me."

The video does not show the rest of the arrest of the Black teenager, nor what became of the young white man who was not arrested.

Police in Bridgewater Township acknowledged on Facebook that the video had "made members of our community upset" and promised an internal investigation.

A spokesperson for the New Jersey attorney general said their office was assisting an investigation launched by the local prosecutor's office.

"The attorney general's office is committed to ensuring thorough, fair, and independent investigations of police use-of-force incidents and police conduct," said the spokesperson.

New Jersey Governor Phil Murphy publicly condemned the police action.

"Although an investigation is still gathering the facts about this incident, I'm deeply disturbed by what appears to be racially disparate treatment in this video," he tweeted on Tuesday.

Racism in law enforcement is a lightning rod issue in the United States, with young Black men at much greater risk from police violence than white men.

Viral footage of the police killing of George Floyd, a Black man, in 2020 sparked nationwide protests and calls for reform of law enforcement.

Steffie Bartley, Northeast Regional Director of the anti-racist National Action Network, condemned what he called the "implicit bias" seen in the Bridgewater video.

"Why was the young Black man on the ground with handcuffs while the young white man was sitting on the couch as if he were overseeing?" he said in a statement.