Police are appealing for information after a suspected hit and run in Olney on Wednesday morning.
At about 6.50am, a man was found with a serious head injury at the side of his stationary car which was parked in Olney High Street, near the Nationwide building society.
Officers are investigating the circumstances of how the victim sustained the injury and would like to speak to anyone who may have witnessed a coach travelling in the area at the time.
The victim, a 44-year-old man from the Lavendon area, was taken to Milton Keynes Hospital. His condition is described as stable and his injuries are not believed to be life-threatening.
Sergeant Simon Hills, from the Thames Valley Police Joint Operations Unit for Roads Policing, said: “We are investigating how the man came to be injured beside his vehicle.
“At first it was unclear whether the man was struck by a vehicle or the victim of an assault. After enquiries at the scene, we have concluded the man was the victim of a fail to stop road traffic collision.
“We do not know whether the driver of the vehicle which collided with the man was aware that he or she had been involved in a collision. We would urge anybody who saw anything which may be useful to the investigation to get in touch with us as soon as possible.
“We would like to thank the public for their patience as the incident caused some disruption during the rush hour.”
The High Street was closed to traffic for around four hours while officers examined the scene.
Anybody with any information about the collision should contact investigating officer PC Samantha Silk from Roads Policing on 101.