A man has died in hospital after being restrained by officers who attended reports of a "loud disturbance" involving violent threats in north London.
The 44-year-old, who has not yet been named, was handcuffed after becoming "agitated" on Waldegrave Road in Hornsey last Thursday.
The man was taken to hospital but died on Friday evening, the Met Police said.
Det Ch Supt Treena Fleming said she was "deeply saddened" by the death.
The Independent Office for Police Conduct (IOPC) has launched an investigation "to establish all of the circumstances" around the incident.
Body-worn video footage
It said all the police officers involved were being treated as witnesses.
IOPC regional director Sal Naseem said: "We have also gathered and viewed some of the officers' body-worn video footage.
"Our investigation is still in its early stages and we continue to gather evidence to establish what happened."
The Met said officers were called at 19:35 GMT following reports of a loud disturbance including threats of violence at a residential address.
The London Ambulance Service was then called as the man's medical condition worsened, the Met said.
It added: "He was transported to a north London hospital in a critical condition. Despite the best efforts of hospital staff, he died the following day.
"The man who called police did not require hospital treatment."