An off-duty police constable was killed after he was attacked while on his way home from a night out, police said.
A murder investigation has been launched after 28-year-old Pc Gareth Francis was assaulted in Edgeley, Greater Manchester, in the early hours of Sunday.
Two men have been arrested on suspicion of his murder.
Police were called to a report of an assault on Castle Street, Edgeley, at around 1.20am. Emergency services attended the scene within minutes and discovered Pc Francis with a serious head injury. The officer was walking home from a night out with friends when he was attacked, police said.
Paramedics treated Pc Francis at the scene and he was taken by ambulance to Stepping Hill Hospital, Stockport, where he died shortly afterwards. Detectives are now appealing for witnesses to the attack.
A post-mortem examination will take place later to establish the cause of death.
Two men, aged 20 and 21, both from the Stockport area, were arrested on suspicion of murder and both remain in custody for questioning.
Stockport Divisional Commander, Chief Superintendent Chris Sykes, said: "First and foremost I would like to pass on my condolences to both Gareth's family and his colleagues in South Manchester. Gareth was a dedicated police officer with six years' experience and he will be greatly missed by his colleagues.
"However, the loss will be even greater for Gareth's family and I would like to reassure them that we have a team of detectives working round-the-clock now to establish exactly what happened this morning."
Anyone with information is asked to call GMP's Major Incident Team on 0161 856 9283 or Crimestoppers on 0800 555 111.