Stand Up To Racism protesters are planning a vigil outside a London police station on Monday after a black man died following a police chase.
Campaigners say they are "enormously concerned and angered" over the death of Rashan Charles over the weekend.
Unverified footage on social media appeared to show at least one police officer attempting to restrain Mr Charles on the floor of a shop, in Kingsland Road, east London, at 1.45am on Saturday.
Metropolitan Police said the 20-year-old was seen "trying to swallow an object" and that an officer "sought to prevent the man from harming himself".
Mr Charles was later pronounced dead in hospital.
The police watchdog is investigating.
Speaking to those gathered at the vigil outside Stoke Newington Police Station, the Borough commander for Hackney, Chief Superintendent Simon Laurence, offered his condolences to Mr Charles's family.
He added: "I understand the community want answers about what happened and no explanation can come quickly enough for a family in mourning.
"This is now subject to an independent investigation by the Independent Police Complaints Commission (IPCC).
"It is their job to investigate this incident and their work started on Saturday."
Mr Laurence said the police officers understood they would be held to account for their actions.
He added that he appreciated that some members of the local community had been impacted by the death and that he had spoken with community representatives to hear their concerns.