As one of the officers stands guard over his partner, a second man wearing a surgical mask can be seen lurking in the background; he appears to lunge at the cop when his back is turned, but suddenly stops just as the filmer loudly announces that he is recording the arrest.
However the man then turns around and sneaks behind the officer again, but this time unleashes two blows into the back of the officer's head, before fleeing up the street.
WARNING: Graphic Content
Luckily for the assailant, the officer reaches for his Taser and fires rather than his sidearm.
As he flees, some of the crowd laugh and cheer, encouraging him to run.
According to CBS News, police caught up with the suspect, later identified as 31-year-old Nelson Jiminez, and arrested him; he allegedly kicked an officer in the groin while resisting arrest.
He was charged with assault on a police officer, obstructing governmental administration, assault, disorderly conduct and harassment.
Police said another suspect, 25-year-old Brandee Isom, also got involved and punched an officer in the jaw; she was charged with assault on a police officer, and obstructing governmental administration.
Video of the attack was shared by a number of NY officials, who condemned it.
Police Chief Terence Monahan tweeted: "Proud of the @NYPD52Pct cop and his fellow Finest for chasing and arresting this cowardly individual for assault on an officer. We'll be working closely with @BronxDAClark to ensure he's fully prosecuted. Think again if you believe you can get away will this behavior in NYC."
Councilman Chaim Deutsch added: "While police officers are heroically putting themselves in harms way to keep us safe, this man decided to attack a cop on the job. Are you kidding me?! A despicable, cruel, and low thing to do."