Alongside the peaceful protests and images of destruction in the wake of the death of George Floyd, there have also been disturbing videos, photos and reports of police officers appearing to use excessive force and violence against demonstrators.
The incidents have raised questions about whether some officers are responding with an inappropriate use of force, forgoing training tactics and becoming overly hostile.
An arrest in Atlanta of two college students Saturday night, as a citywide curfew was going into effect, was so excessive, police officials said Sunday, that two officers involved were fired and three others were placed on desk duty.
A video of the incident showed one of the students getting dragged from the 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 Atlanta Police Chief Erika Shields told reporters that "how we behaved is unacceptable," reported NBC affiliate WXIA.
"This is not who we are," Shields said. "I am truly sorry to those individuals. We are still working to get it right."
Other cities grappling with unrest have been faced with their own policing complaints during protests. An investigation was opened in New York City after video showed a pair of New York Police Department SUVs plowing into a crowd Saturday in Brooklyn.
Protestors had thrown traffic cones and other items at one of the SUVs when a second vehicle arrived and drove slowly through a crowd. But the first SUV then barreled through a barricade at a higher speed, forcing the crowd to disperse and pushing some people to the ground. Multiple city officials told NBC News there were no injuries.
Initially, New York City Mayor Bill de Blasio said that while he wished the officers didn't respond in such a manner, the incident was not started by them but by "a group of protesters converging on a police vehicle, attacking that vehicle. It's unacceptable."
The officers' actions, however, horrified Rep. Alexandria Ocasio-Cortez, D-N.Y., who tweeted that people could have been killed and "NO ONE gets to slam an SUV through a crowd of human beings."
On Sunday morning, de Blasio shifted his criticism onto the officers, saying that an independent review would examine their actions and what could have been done differently.
"There were many things done right by the NYPD," de Blasio said, adding, "There were also mistakes that must be investigated."
But that wasn't the only incident that has come under scrutiny, throughout the last few days of protests.
NYPD officers in Brooklyn were seen using batons and pepper spray against protesters as people fell to the ground amid the confusion.
Sherrilyn Ifill, the president and director-counsel of the NAACP Legal Defense Fund, shared a video Saturday that appeared to show New York protesters with their hands up, and an NYPD officer pulling a black protester's mask down and pepper-spraying him in the face.
The NYPD did not immediately respond to a request for comment about the incident. In a tweet Sunday, NYPD Commissioner Dermot Shea defended the nation's largest police force, writing, "I'm extremely proud of the way you've comported yourselves in the face of such persistent danger, disrespect, and denigration."
But no matter how chaotic the situation, officers must rely on their training and do everything in their power to de-escalate a situation, said George Kirkham, a former police officer and professor emeritus at the College of Criminology and Criminal Justice at Florida State University.
"You cannot start meting out extrajudicial punishment," Kirkham said.
Aggressive tactics have also been recorded in Minneapolis, which became the center of daily protests since Floyd's death at the hands of a city police officer seen kneeling on his neck as he cried out, "I can't breathe." Floyd later died. While that officer, Derek Chauvin, was fired Tuesday and arrested Friday on charges of third-degree murder and manslaughter, Floyd's death has set off larger protests against police brutality and racism in policing that have rippled in dozens of states and even across the globe.
But the largely peaceful protests have been overshadowed by hundreds of arrests, destruction to businesses and police property, including a precinct house and several cars.
Officers in Minneapolis were filmed Saturday patrolling through neighborhoods ahead of an 8 p.m. curfew, demanding people standing on their properties "go inside now." One officer can be heard yelling, "Light 'em up," before other officers appear to fire paint projectiles at residents standing just outside their front doors, who then scatter inside. (The local curfew does not apply to people on their own property.)
Throughout the night, police officers unleashed tear gas, pepper spray and rubber bullets on protesters. Several members of news organizations, including reporters with NBC News, said they were hit.
According to a tally by The Reporters Committee for Freedom of the Press, at least 17 members of the news media were injured Saturday in incidents, and the group released a statement asking authorities to refrain from deliberately targeting press.
Minneapolis Police Chief Medaria Arradondo told reporters late Saturday that arrests being conducted by officers were "strategic" and that "folks who are willing to comply and leave our city and ensure that they're not harming it, that's OK. We're restoring hope back into the city."
Other incidents across the country have gone viral, including a police officer in Salt Lake City, Utah, seen shoving an elderly man holding a cane as law enforcement officials tried to disperse demonstrators Saturday night. Other officers in riot gear then helped the man up, reported a local ABC affiliate that recorded the scene.
Salt Lake City Police Chief Mike Brown said in a video statement Sunday that the department has identified the officer who knocked down the man and opened up internal affairs and civilian review board investigations.
"I want to say, this is not what we expect from Salt Lake City PD," Brown said, adding that he apologized to the man and it "was hard to watch what happened." He also said for the most part, officers were "courageous" in how they reacted Saturday during protests in the city.
An officer in Seattle was recorded Saturday night with his knee on the neck of a man as he was being arrested in the middle of a street. Police were reportedly responding to a break-in at a T-Mobile store.
Bystanders could be heard shouting, "Get your knee off his neck!"
Seattle police officials did not immediately return a request for comment about the video and NBC News does not know what happened directly before it was recorded.
In Los Angeles, videos were shared online Sunday of an apparent police SUV accelerating forward in the street and coming into contact with a person who fell underneath the front of the vehicle. The person could be seen getting up amid screams from the crowd as the SUV backed up and drove off.
The Los Angeles Police Department did not immediately comment about the video.
Seth Stoughton, a law professor at the University of South Carolina and co-author of "Evaluating Police Uses of Force," said police departments are making a mistake when officers immediately employ a show of force at protests, when that's exactly what people are demonstrating against.
But the fact that some cities have rolled out curfew orders — and some people are willfully ignoring them — has only ratcheted up the response by police officers, who have an expanded authority to make arrests of people that defy orders.
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Shields was also praised for how she stopped to listen to those in a crowd in Atlanta on Friday night as they aired their concerns over policing, including the lack of arrests of all the officers in the Floyd case.
"Had they not been cops," Shields told protesters, "they would have been arrested."
Stoughton said it's important that law enforcement agencies anticipate protesters' reactions and engage with them in a meaningful way so that tense dynamics can be defused.
"Taking a responsive approach that validates the reason protesters are out and lets them know they're being heard can forestall an escalation," Stoughton said.
But "once things have escalated, it's probably too late for that," he added. "By the time they're throwing Molotov cocktails, it's too late."