A man is in a critical condition in hospital after he fell ill while being kept in police cells and was found to have a head injury.
The 22-year-old man was arrested after police were called to a disturbance on Mount Pleasant Road, Masborough, Rotherham, on Saturday night.
He was detained overnight at Main Street police station but an ambulance was called when he became unwell.
The Independent Police Complaints Commission (IPCC) has been informed.
South Yorkshire Police said: "It has now been identified that the man had suffered a serious internal head injury. It is believed that this injury occurred during the earlier incident on Mount Pleasant Road.
"His condition is described as critical.
"The IPCC have been informed as a matter of routine as the man was in police custody when he took ill."
Three Rotherham men have been charged with wounding with intent.
James William Garbutt, 27, of Whitegate Walk, Brett David Garbutt, 22, of Brown Street and Karl Charnock, 27, of Healey Grove Road, appeared before Rotherham magistrates and were remanded in custody until 20 August.