A man is in a critical condition in hospital after police restrained him when they were called to reports of him "setting fire to himself".
A probe has now been launched into the incident, which saw the man in his 50s lose consciousness in Camden, north London.
Metropolitan Police were called to reports of a man "behaving erratically, threatening members of the public and setting fire to his clothing" and, after he was detained under the Mental Health Act, the man was taken to a medical facility.
But he became agitated there and was restrained by officers, who used PAVA spray (similar in use to pepper spray to incapacitate someone) on him.
He became unwell and lost consciousness and was given medical attention before he was rushed to hospital in a critical condition, where he remains.
The Independent Office for Police Conduct (IOPC) has launched an independent investigation into the incident which took place on Monday morning, reports My London.
Metropolitan Constabulary acknowledged the incident will be "incredibly concerning to the public".
A spokesperson for the force said: "As is procedure in these circumstances, the Met’s Directorate of Professional Standards were informed and alerted the Independent Office for Police Conduct, who have launched an independent investigation."
Superintendent Annmarie Cowley, from the Met's Central North Command, said: "We appreciate this incident will be incredibly concerning to the public. Please know we are offering every assistance to the IOPC in their investigation and, due to their important ongoing work, will not be able to comment further at this time."
An IOPC spokesperson said: "An independent investigation is underway into the actions of Metropolitan Police Service (MPS) officers during an incident where a man was restrained at a hospital in north London on Monday 3 April. MPS officers responded to reports from members of the public on Monday morning of a man behaving erratically and setting his clothes on fire on Euston Road, NW1.
"The man was taken to the medical facility to be assessed where he became agitated at times and later officers have used PAVA spray and restrained him.
"The man became unconscious and was then given medical attention. We understand the man remains in a critical but stable condition in hospital.
"After being notified by the MPS’ Directorate of Professional Standards later that afternoon, we sent investigators to Islington police station to attend the police post-incident procedures and declared an independent investigation.
"Our investigation is in its initial stages and we have begun gathering evidence and have secured officers’ body worn video footage."
