A New York police officer appeared to brandish his gun during protests Sunday night in downtown Manhattan, sending demonstrators scrambling, and a video of the incident is being investigated by the department.
A police union has since said a subsequent video showed the officer was reacting to his supervisor being attacked. The incident continues to fuel the debate about police tactics across the U.S.
Earlier on Monday, Mayor Bill de Blasio called the officer's actions "absolutely unacceptable," and said that while claims of police use of excessive force are "rare," they "must be addressed in every instance."
"Any officer who should not be wearing that uniform needs to get off this force," de Blasio said at a news conference Monday.
NBC News has not confirmed what was happening between the officer and the protesters in the video. The officer has not been identified.
But after the original clip was widely shared on social media, a new, longer video of the incident emerged that appeared to show the officer's supervisor being struck by a brick.
The Police Benevolent Association of the City of New York, which represents 24,000 rank-and-file officers, posted the clip to its Twitter account and said: "Now we have the full story: this police officer unholstered his weapon only after his supervisor was nearly killed with a brick. #FactsMatter."
New York and other cities have seen days of protests since George Floyd, a black man, died in police custody in Minneapolis last week. Some demonstrators in several cities have clashed with police, leading to a wave of fresh complaints of excessive use of force.
Some of the incidents have been captured on video and in photos, stoking further outrage about what protests call police brutality.
One protester told NBC News that despite the demonstrations around Union Square in Manhattan, that particular block seemed peaceful at first, and people were confused and started running when they saw the officer holding out his gun.
The incident follows others now under scrutiny, including a pair of NYPD SUVs apparently seen plowing into a crowd Saturday in Brooklyn.
Initially, de Blasio blamed a group of "protesters converging on a police vehicle, attacking that vehicle" for triggering the event.
But the mayor has since shifted his criticism onto the officers, saying that an independent review would examine their actions and what could have been done differently. Multiple city officials told NBC News there were no injuries.
State lawmakers on Monday demanded the firing of two police officers involved in the shoving of a young protester in Brooklyn on Friday night. It's unclear what led up to the encounter, but the protester, who identified herself on social media as Dounya Zayer, said she was hospitalized.
State Sen. Zellnor Myrie, a Democrat from Brooklyn, tweeted that the officers, whom he identified, "must be removed."
Initially, PBA President Pat Lynch defended officers in a response Monday to New York Gov. Andrew Cuomo, saying that officials appear to be "wrongly blaming the chaos on the cops."
NYPD Commissioner Dermot Shea has called the video "disturbing," but didn't immediately respond to a request about an independent investigation that de Blasio said had been opened.
On Monday, Shea told NBC's "TODAY" show that he was also "troubled" by the incident involving the SUVs.
But, he added, police have been overwhelmed by the protesters, who he says are also goading the officers.
"It is inappropriate for protesters to surround a police vehicle and threaten police officers," Shea said. "That's wrong on its face and that hasn't happened in the history of protests in this city."
In other cities, officials have acted swiftly to reprimand officers seen using overly aggressive tactics.
Atlanta Police Chief Erika Shields and Mayor Keisha Lance Bottoms announced Sunday that two officers had been fired and three others placed on desk duty in an excessive force case from Saturday night.
A video of the incident showed one of two college students getting dragged from a car, while the driver, who remained behind the wheel, was tased and then pulled out of the vehicle. It's unclear what preceded the incident, but Shields apologized to the students. "We are still working to get it right," she added.
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Other accounts have emerged of police using pepper spray, rubber bullets, batons and other items against protesters, whether in response to provocations, such as looting or vandalism, or seemingly unprovoked.
Carl Marcel, a protester and photographer, said he was out amid the peaceful protests in downtown Seattle on Sunday afternoon when he saw an officer on a bicycle physically restrain a man who was on the sidewalk in front of him.
"He was just walking. I did not notice anything happening beforehand that would make the cop feel provoked," Marcel said. "It all happened out of the blue."
Photos taken by Marcel show the officer appearing to pull the man down onto the sidewalk. Marcel said the man was detained and handcuffed, and afterward, a crowd gathered with their hands up, and officers "started pepper-spraying and throwing smoke bombs."
Seattle police did not immediately respond to a request for comment Monday.
Another protester with Marcel, Raven Hamilton, said she witnessed the same incident.
"It appeared the officer became angry that the protester was in his way and grabbed him by the neck and they were on the ground before the protester involved had a chance to react," Hamilton said.
She said she saw another officer on a bike kick a protester in the head as he was tying his shoes on the sidelines of a mass gathering.
"I think the message they are trying to convey is that they do these things because they can," Hamilton said of police, "and are trying to exert their authority."