Minneapolis police have clashed with protesters following the death of an unarmed black man in police custody.

Police fired tear gas and protesters threw rocks and sprayed graffiti on police cars.

Video of the death shows 46 –year-old George Floyd groaning “I can’t breathe” as a policeman kneels on his neck.

Four police officers have been fired, with Mayor Jacob Frey saying that being black “should not be a death sentence”.

The incident echoes the case of Eric Garner, who was placed in a police chokehold in New York in 2014. Eric Garner’s death became a rallying call against police brutality and was a driving force in the Black Lives Matter movement.

Violent clashes began in the afternoon on May 26, when hundreds of people came to the intersection where the incident had taken place on May 25.

Organizers tried to keep the protest peaceful and maintain coronavirus social distancing, with demonstrators chanting “I can’t breathe,” and “It could’ve been me”.

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A crowd of hundreds later marched to the 3rd Precinct, where the officers involved in the death are thought to have worked.

Squad cars were sprayed with graffiti and protesters threw stones at the police building. Police fired tear gas, flash grenades and foam projectiles.

Police said one person had suffered non-life-threatening injuries after being shot away from the protest area but gave no further details.

Officers responding to reports of the use of counterfeit money had approached George Floyd in his vehicle.

According to police the man was told to step away from the vehicle and physically resisted officers.

A police statement said: “Officers were able to get the suspect into handcuffs and noted he appeared to be suffering medical distress.”

The video taken at the scene does not show how the confrontation started.

It shows a white officer using his knee to pin George Floyd to the ground by the neck.

George Floyd groans “please, I can’t breathe” and “don’t kill me” as bystanders urge officers to let him go.

He ceases to move and an ambulance arrives to take him to hospital where he later died.

Mayor Jacob Frey said it was the “right call” to fire the officers.

He said: “Being black in America should not be a death sentence. For five minutes we watched as a white police officer pressed his knee into the neck of a black man. For five minutes. When you hear someone calling for help, you are supposed to help.”

The FBI is investigating the incident and will present its findings to the Minnesota state’s attorney for possible federal charges.

Allegations of police brutality have been constantly highlighted since the start of the Black Lives Matter movement. It began after the acquittal of neighborhood watchman George Zimmerman in the shooting death of African-American Trayvon Martin in February 2012.