There have been protests in Minneapolis between police and demonstrators after an unarmed black man in police custody in the U.S. city died Monday.

Police fired tear gas, and demonstrators hurled rocks at police vehicles and sprayed graffiti.

Video of the death shows George Floyd, 46, who groans “I can not breathe” as a white policeman kneels on his neck.

Four police officers were shot and the mayor said that being black “should not to be a death sentence.”

Mayor Jacob Frey also called on prosecutors to file criminal charges against Mr Floyd’s filmed policeman.

The incident resembles the case of Eric Garner who, in 2014, was put in a New York police chokehold. His death became a rallying call for police brutality, and was a driving force in the movement for Black Lives Matter.

Officers reacting to allegations of the use of counterfeit money had confronted Mr Floyd in his car.

He had been told to step away from the vehicle and physically resisted officers according to police.

Mr Floyd groaned “please, I can’t breathe,” and “don’t kill me,” as bystanders are urging officers to let him go.

He stopped moving and an ambulance arrived to take him to hospital where he died later.