An elderly protester was the latest victim of the police tactics being used against anti-racism protesters across the US, sparked by the death of George Floyd.
Video shows the 75-year-old, white-haired man bleeding from a head injury after he was pushed by a police officer in Buffalo, New York.
The video, filmed by local radio station WBFO, shows the man walking towards a line of police officers who were clearing people from a city square as a curfew started.
Two officers can be seen pushing at the man, one using his baton and the other using his hand, forcing him to fall backwards and hit his head on the pavement.
The video shows the officer with the baton start to lean over him before he is motioned away by another officer. Someone is heard calling for a medic.
On Friday the man, who has not been identified, was in a stable but serious condition at Erie County Medical Centre Hospital in Buffalo, and two police officers had been suspended.
“Police officers must enforce - NOT ABUSE - the law,” New York Governor Andrew Cuomo tweeted, referring to the Buffalo incident, which happened on Thursday. He said what he had seen on the video was “wholly unjustified and utterly disgraceful”.
The Buffalo incident has been called a sign of what is wrong with policing in America, in a week that has seen peaceful protests, violent looting and demonstrations across the country.
Floyd died in Minneapolis on May 25 after police officer Derek Chauvin was recorded kneeling on Floyd’s neck for nearly nine minutes during an arrest.
Mr Chauvin, who has since been suspended, now faces second-degree murder charges. Three others have also been charged.
“The casual cruelty demonstrated by Buffalo police officers tonight is gut-wrenching and unacceptable,” John Curr, the Buffalo chapter director for the New York Civil Liberties Union, said.
Mr Curr said it should be a “wake-up call” for city leaders to address police violence.
Buffalo police initially stated the man was “injured when he tripped & fell,” but police captain Jeff Rinaldo later said an investigation had been opened by the police misconduct unit.
The Mayor of Buffalo, Byron Brown, said he was “deeply disturbed” by the video.
“After days of peaceful protests and several meetings between myself, police leadership and members of the community, tonight’s event is disheartening,” he said.