Police in east London made some arrests after they were attacked with bottles during a protest over the death of man who had been detained a week earlier, police said on Saturday.
Rashan Charles, 20, died on July 22 after he was chased by a police officer who attempted to remove an object from his mouth or throat.
A protest over his death in the borough of Hackney turned violent on Friday night when bottles and other objects were thrown at officers and small fires were started, police said.
Local businesses were damaged and police in riot gear and some on horseback were called in to help clear the area.
A police spokeswoman said she could not immediately confirm the number of arrests.
The BBC said some protesters carried Black Lives Matter placards.
An independent police complaints agency has said it will investigate "thoroughly and rigorously" the incidents that led to the death of Charles.