Graphic body-cam footage has been released of the moment a police officer in Washington shot a unarmed, black man riding a motorbike.
Terrence Sterling, 31, of Fort Washington, Maryland, died on September 11 after being shot by 27-year-old officer Brian Trainer.
Police say a Metropolitan Police Department officer shot him after Sterling rammed a squad car with his motorbike.
In the footage, which is nearly six minutes long, Sterling can be seen lying on the ground in a pool of blood.
An officer takes off Sterling's jacket, helmet and his shirt and begins performing CPR on him.
Attempting to keep Sterling conscious, the officer shouts: "Come on, man, keep breathing.
"Look at me. Keep looking at me."
In the background, a woman screams loudly as ambulances approach.
Police say the incident took place at 4.20am in Northwest, Washington on September 11.
An officer saw a motorcyclist driving recklessly, according to NBC Washington .
As Trainer exited his squad car from the passenger side, intending to stop the biker, police reports suggest Sterling drove straight into the passenger door.
It is at this point that Trainer, who has been with the police department for four years, fired - hitting Sterling.
Ambulances were dispatched at 4.30am, according to officials. Sterling was taken to Howard University Hospital where he was pronounced dead.
Trainer has been placed on administrative leave as an investigation into the incident continues.
It is believed that he did not turn on his camera until the shot had been fired.
Mayor Muriel Bowser deemed the footage to be "in the public interest and consistent with the goals of the District's [body-worn camera] program to create broader accountability between law enforcement and communities, and to maintain open and transparent government."
But the DC Police Union condemned the release of the video.
Chairman Matthew Mahl: "This decision places these officers in danger of misguided retaliation fueled by a false media narrative, and is a completely unacceptable action.
"The lives of our members are not pawns in some political game, to be throw to anti-police special interest groups in the pursuit of an unlikely re-election bid for a flawed administration."
Earlier this month, in the US city of Charlotte, disabled black man Keith Lamont Scott was killed by police.
Violent demonstrations have since engulfed the city.
Protesters took to the streets on Tuesday and Wednesday nights as widely differing accounts of the shooting emerged.
Police said Scott, 43, was armed and ignoring officers' orders when he was gunned down, while the victim's family and a witness said he was holding a book, not a weapon.
Authorities have not released any video of the incident, but the city's mayor said they plan to.
Protesters took to the streets on Tuesday and Wednesday nights as widely differing accounts of the shooting emerged.
Police said Scott, 43, was armed and ignoring officers' orders when he was gunned down, while the victim's family and a witness said he was holding a book, not a weapon.
Authorities have not released any video of the incident, but the city's mayor said they plan to.
The deaths were the latest incidents to raise questions of racial bias in US law enforcement, and they stoked a national debate on policing ahead of the presidential election in November.
High-profile police shootings in New York, Chicago, Ferguson, Missouri, and other cities have sparked more than two years of largely peaceful protests punctuated by days of unrest and arson while giving rise to the Black Lives Matter civil rights movement.
Investigations have been opened in both cities, and the US Justice Department has started a separate probe into the Oklahoma incident to see if officers' use of force amounted to a civil rights violation.
