A report was received by police at around 3.30am this morning (Tuesday August 16) that a man had been found unconscious in Lazarus Court in Doncaster.
The 23-year-old was taken to hospital with serious head injuries and his condition is described as life threatening.
The injuries are thought to have been sustained following an assault but police said they are still investigating the circumstances of the incident at this time.
A spokesman said: "A scene has been identified at the location as officers begin to investigate the circumstances of the incident."
Anyone with information should call 101 quoting incident number 89 of 16 August 2016.