Police were called to a report of a collision and stabbing in Pembury Road in Gloucester at 7.15am this morning.
A 44-year-old man has been taken to Southmead Hospital in Bristol with life threatening injuries.
A 49-year-old Gloucester man has been arrested on suspicion of attempted murder and remains in police custody at this time.
Police believe the injured man and arrested man know each other and we do not believe this to be a road rage type incident.
Police have not said whether the man was stabbed and then run over or run over and then stabbed.
Road closures are in place while the investigation continues. These closures will apply for vehicles and pedestrians until further notice.
Stroud Road was closed for several hours between A38 Southern Avenue / A4173 Stroud Road / Reservoir Road and Pembury Road. The road closures were lifted at 13:30.
Stagecoach say bus services 9, search 62 and 63 were also diverted while road closures were in place.
Anyone with any information is asked to call police on 101 or Crimestoppers on 0800 555 111.