A 59-year-old was found in a critical condition between Wood Farm Road and Nuffield Road this morning.
Just after 6am, officers attended Wood Farm Park following a report of a man calling for help.
The victim, a 59-year-old man from Oxford, was found with a head wound in a critical condition beside a path in the park.
The victim was taken to the John Radcliffe for further treatment, but he sadly died soon afterwards.
His next of kin have been informed.
An 18-year-old man from Oxford has been arrested on suspicion of murder and remains in police custody this afternoon.
Head of Criminal Justice and senior investigating officer, Detective Superintendent Craig Kirby, said: “We are in the very early stages of this investigation, which appears to be a targeted attack.
“We have arrested an 18-year-old man from Oxford on suspicion of murder and he remains in police custody.
“I would ask anyone who may have information about this incident or was in the area at around 6am this morning to please contact us as soon as possible.
“Also, if you were driving in the area around the time of this incident and have a dash-cam or if you live in the area and have a CCTV camera or a video doorbell, please check your recordings in case it has captured something that could assist our investigation.
“A large scene watch is likely to be in place for some time, which is likely to have an impact on local residents as it includes the park, Pether Road and Bonar Road, all of which are shut at this time.”
Thames Valley Police told JACKfm that there is no link to an incident earlier this month where a man was stabbed in the leg in the same area, but officers ‘are keeping an open mind’ as the investigation continues.