Four Minneapolis police officers have been fired after one of them was filmed kneeling on the neck of an unarmed black man who later died in hospital.
The video, shot by bystanders, shows the man pleading for help as a white officer kneels on his neck.
“Please, please, please, I can’t breathe. Please, man,” the man is heard telling the officer.
The incident, which happened on Monday, is under investigation by the FBI and state law enforcement authorities.
It has drawn comparisons to the case of Eric Garner, an unarmed black man who died in 2014 in New York after he was placed in a chokehold by police.
Minneapolis Mayor Jacob Frey said the decision to sack the officers involved in the arrest was “the right call”, and apologised to the black community
“Being black in America should not be a death sentence,” Mr Frey wrote on Facebook.
“For five minutes, we watched a white officer press his knee into a black man’s neck. Five minutes. When you hear someone calling for help, you’re supposed to help. This officer failed in the most basic, human sense.”
The man who died was identified as George Floyd by Ben Crump, a prominent civil rights and personal injury attorney who said he had been hired by Mr Floyd’s family.
The bystanders became increasingly agitated as the man pleaded with police. One told officers they needed to let him breathe. Another yelled at them to check the man’s pulse.
“We all watched the horrific death of George Floyd on video as witnesses begged the police officer to take him into the police car and get off his neck,” Mr Crump said in a statement.
“This abusive, excessive and inhumane use of force cost the life of a man who was being detained by the police for questioning about a non-violent charge.”
Charles McMillian, 60, of Minneapolis, said he saw police trying to get Mr Floyd into the back of the squad car, and heard him tell them he was claustrophobic.
After having the officer’s knee on his neck, Mr McMillian said, Mr Floyd started calling his mother’s name, “and then he died”.
“It’s sad because it didn’t have to happen,” Mr McMillian said. Minneapolis Police Chief Medaria Arradondo said the department would conduct a full internal investigation.
Experts on police use of force said the officer clearly restrained the man for too long. They noted he was under control, and not fighting.
Andrew Scott, a former police chief who now testifies as an expert witness in use-of-force cases, called Mr Floyd’s death “a combination of not being trained properly or disregarding their training”.
“He couldn’t move. He was telling them he couldn’t breathe, and they ignored him,” Mr Scott said. “I can’t even describe it. It was difficult to watch.”
In the case of Eric Garner, the officer involved said he was using a legal manoeuvre called “the seatbelt” to restrain Mr Garner, who he said had been resisting arrest.
But the medical examiner referred to it as a chokehold in the autopsy report and said it contributed to his death. Chokeholds are banned under New York police policy.
A grand jury later decided against indicting the officers involved in Mr Garner’s death, sparking protests around the country.
In Minneapolis, kneeling on a suspect’s neck is allowed under the department’s use-of-force policy for officers who have received training in how to compress a neck without applying direct pressure to the airway.
It is considered a “non-deadly force option”, according to the department’s policy handbook.
A chokehold is considered a deadly force option and involves someone obstructing the airway. According to the department’s use-of-force policy, officers are to use only an amount of force that would be objectively reasonable.
The Hennepin County Attorney’s Office, which would handle any prosecution of police on state charges, said in a statement that it was “shocked and saddened” by the video and pledged to handle the case fairly.
The death came amid anger over the killing of Ahmaud Arbery, who was fatally shot in Georgia. Two white men, a father and son, have been charged with murder.
Mr Crump also represents Mr Arbery’s father.