A suspect has died in police custody after officers used CS spray to detain him.
Greater Manchester Police said the man, in his thirties, was arrested by officers following an alleged domestic disturbance in Oldham at around 11.35pm on Friday.
A police spokesman said officers "used CS spray to detain the man" during the arrest.
However, he was found to be unresponsive in the back of the police van by the time he arrived at the custody station, a distance of roughly four miles.
He was pronounced dead later in hospital.
The Independent Office for Police Conduct (IOPC) are now investigating.
Chief Superintendent Neil Evan said: "Last night we received a report of a domestic disturbance at a property in Oldham.
"Local officers swiftly responded to the incident and arrested a man on suspicion of breach of the peace.
"During the arrest attempts, the officers deployed CS spray before putting him in the back of a van.
"On arrival at Ashton Police Station, the man was found to be unresponsive and he was taken to hospital where he was sadly pronounced dead.
"We have since been providing his family with support from specially trained officers at this difficult time.
"We have made a mandatory referral to the IOPC who are independently investigating and we will continue to co-operate with them fully."
It is not known whether the suspect, who has not been identified, had any mental illness.