The police watchdog has launched an investigation after a young black man died in a shop after being chased by police.
Metropolitan Police said the 20-year-old man, who has been named locally as Rashan Charles, was seen "trying to swallow an object" and that the officer "sought to prevent the man from harming himself".
Unverified footage on social media appeared to show at least one officer attempting to restrain the suspect on the floor of the shop, in Kingsland Road, east London, at 1.45am on Saturday.
He was later pronounced dead in hospital.
Chief Superintendent Simon Laurence, borough commander for Hackney, urged people to keep up-to-date with information from the Independent Police Complaints Commission (IPCC) amid concern over "speculation" about how the man died.
Mr Laurence said: "In the early hours of Saturday officers attempted to stop a car on Kingsland Road, E8.
"A man, who was in the car, was pursued on foot before entering a shop where he was seen to be trying to swallow an object. He was then taken ill.
"He was taken to hospital by the London Ambulance Service where, sadly, he died later that morning. Our thoughts remain with his family and friends.
"The Independent Police Complaints Commission (IPCC) has launched an independent investigation to establish what happened and has viewed the officers' body worn video.
"There is likely to be speculation over the next few days regarding what led to this man becoming ill, so I would encourage people to keep up-to-date with the IPCC's statements, as and when they are released.
"All police officers are fully aware that they will be asked to account for their actions - officers are not exempt from the law and we would not wish to be."
The IPCC said it had launched an independent investigation at 3.10am on Saturday - less than an hour and a half after police pursued the man.
It said it had obtained evidence "which indicates an object was removed from his throat at the scene".
The shop, which is known locally as the red shop on Kingsland Road, was open on Sunday.
Several floral tributes had been laid outside the barber shop next door.
Erem, who owns the barber shop but did not want to give his full name, said he had seen Mr Charles, known as Rash, about 15 hours before he died.
"He was a humble young man," Erem said, "he was really known in the area."
He said the young man knew how to speak to people: "He was very mature for his age."
"I'm in shock myself," he said, adding he would often speak to the young man outside his shop.
Campaigners from the Hackney Stand Up To Racism have announced a vigil outside Stoke Newington police station from 6pm on Monday amid "concerns" about the circumstances leading to Mr Charles's death.