Police were called by paramedics to a play area at the end of South Street in Wardleworth, Rochdale, on Thursday night.
Officers attended and found a man believed to be in his late 40’s to early 50’s with a serious head injury. He was taken to hospital where he died a short time later.
“We recommend that you do not speculate but rather wait for the facts to be established by the police.”
A Home Office post mortem is due to take place later today.
Detective Superintendent Jon Chadwick, of the Serious Crime Division, said: Our investigation is at an early stage but we are keen to hear from anyone who may have been in the area near to where he was found in Wardleworth last night, as we work to establish how this man came to suffer his head injury.
Superintendent Rick Jackson said: We know local people will be worried when they hear the news of what has happened and we have extra patrols in place to try and reassure the community.
If you have concerns or believe you may have seen, heard or know anything that can assist this investigation then please approach one of these officers.
There has been a lot of speculation on social media about what has happened but I would like to ask that people allow us to investigate this incident and if you have information then please contact police.
Anyone with information is asked to contact police on 101 or alternatively, the independent charity Crimestoppers, anonymously, on 0800 555 111.