Four officers were on top of the man and one officer had his arm wrapped around the man. The officer got up after another officer tapped him on the back and appeared to pull at the back of his shirt.
"While a full investigation is still underway, there is no question in my mind that this immediate action is necessary," NYPD Commissioner Dermot Shea said.
Mayor Bill de Blasio said it was the fastest he'd ever seen the NYPD discipline an officer.
"This is how it needs to be," he said. "The officer who intervened to stop his colleague did exactly the right thing. I commend him. That is what we need to see from all our officers."
Lori Zeno, the man's attorney, said she thinks her client would have been choked to death if the officer hadn't been stopped.
After the video surfaced, an NYPD spokesperson said it was being taken "extremely seriously" and that there was an active investigation underway by the Internal Affairs Bureau.
Police got a call for a man being disorderly on the boardwalk near Beach 113th Street on Sunday morning, officials said. Officers said he was acting erratically when they arrived and resisted when they tried to take him into custody.
Body camera video from the NYPD shows a lengthy interaction between police and men on the boardwalk before the start of the viral arrest video.
"Oh man, this is fun," an officer can be heard saying.
The three pedestrians continue talking to police.
"Touch any of my boys and you are dead," the man who was eventually put into an apparent chokehold said.
One of the other pedestrians chastised the man, saying he doesn't disrespect police.
About 10 minutes after the confrontation began, police took down the man who'd threatened him. It appears he may he have taken something from a recycling bin right beforehand.
"Stop choking him! Stop choking him! Let him go," the other pedestrians screamed.
After being put in an apparent chokehold, the man was walked to an NYPD vehicle where he told police has was bipolar.
While still on the boardwalk, bystanders confronted police.
"He grabbed something and squared off and was gonna hit my officer who's standing over there," an officer can be heard saying. "That's when everything changed. The minute I saw him flex on him, that's when he goes down because we don't get hurt."
The man was treated at a local hospital, police said. Zeno said he was a visible wound on the back of this head.
Charges against the man are pending, police said. It's not clear what the NYPD intends to charge him with, but the man's attorney said it's the suspended police officer who should be charged.
"He's an idiot and he's a bad cop and he needs to go," Zeno said. "He needs to get fired and needs to get prosecuted."
Mayoral spokesperson Freddi Goldstein called the video "very concerning."
"We’re glad the NYPD is immediately launching an investigation to get to the bottom of what happened," she said.
Queens District Attorney Melinda Katz said her office is also investigating.
"There must be zero tolerance for police misconduct," she tweeted. "The Queens District Attorney's Office is aware of the incident in Far Rockaway today. We take these allegations very seriously and an active investigation is underway."
Just days ago amid ongoing protests over police brutality, Gov. Andrew Cuomo signed several police accountability measures into law, including a ban on police chokeholds. The NYPD banned chokeholds in the 1990s.
Warning: Video of the incident may be disturbing to some. Police also shared body camera video.
This story was originally published by Aliza Chasan and Cristian Benavides at WPIX.