A man who was arrested after a reported disturbance at a property has died while in custody, Greater Manchester Police (GMP) has said.
The 57-year-old was detained after officers were called to Argyll Road, Cheadle, Stockport, at about 04:30 BST.
He was taken to a police station but fell ill shortly afterwards, when he was given medical aid and taken to hospital, the Independent Office for Police Conduct (IOPC) said.
It said he died at about 06:50 BST.
Ch Supt Wayne Miller, of GMP, said: “We have made a mandatory referral to the Independent Office for Police Conduct who are independently investigating and we will continue to co-operate with them fully.”
Amanda Rowe, regional director at the IOPC, said: “Our sympathies are with the man’s family and all those affected by his death.
“We have met with family members to explain our role and we will keep them regularly updated.
“Our investigation is obviously at a very early stage and we will be carrying a thorough investigation into all the circumstances.”