After a video of police shoving a 75-year-old white protester who approached them in a city in New York state went viral, two of them were suspended, but all the members of the emergency team resigned in protest.
Their action on Friday amid the protests against police brutality roiling the nation brought to the fore the discontent in law enforcement as they too have been facing attacks and also their use of force.
Endorsing their suspension and calling for their firing, New York Governor Andrew Cuomo called the police action "fundamentally offensive and frightening" and disturbing to the "basic sense of decency and humanity".
In the video shot during a protest on Thursday, the man, Martin Gugino, is seen walking towards a line of police in riot gear advancing in formation against protesters in Buffalo, a city near the Niagara Falls.
As he nears them a policeman shoves him with his baton and another with his hand and he falls backwards and injures his head.
Gugino was hospitalised and his lawyer told the local NBC affiliate, WGRZ, on Friday that he was "alert and oriented".
But responding to the suspensions, all the 57 members of Buffalo's police emergency response team resigned from the unit "in disgust because of the treatment of two of their members, who were simply executing orders", WGRZ quoted police union president John Evans as saying.
Police in most municipal jurisdictions are under the control of the elected leadership. Buffalo Mayor Byron Brown is a Democrat.
While police excesses, especially against minorities, are in focus because of the nationwide protests triggered by the dead of George Floyd, an unarmed African-American man in Minneapolis on May 25 while in police custody, the force have also come under attack.
In the most serious incident in New York City, one police officer was stabbed in the neck and two others were shot on Wednesday night while on patrol to stop looters.
A police officer was shot in the head in Las Vegas and four police officers were injured and a retired police captain killed by gunfire in St Louis, Missouri, on Tuesday.
Police have also been hit with stones, bricks and other objects during protests, while videos are also surfacing every day of police excesses against protesters.
After brazen looting of stores across in New York City on Monday night, Cuomo faulted New York City Mayor Bill de Blasio and called his leadership a "disgrace".
But after he tightened enforcement, he was criticised for police actions and booed on Thursday when he spoke at a memorial service for Floyd.
(Arul Louis can be contacted at arul.l@.in and followed on Twitter @arulouis)
( With inputs from IANS )