A man has been charged with attempted murder after a policeman was hit by a car.
Plain clothes officer John Gavin was on duty in Market Square, Aylesbury, on Tuesday when he was hit by a red Vauxhall Astra, which left the scene.
The 30-year-old was taken to hospital with head injuries and discharged with concussion.
Thames Valley Police has charged Corey Allard, of no fixed address, with attempted murder and dangerous driving.
The 20-year-old has also been charged with two counts of grievous bodily harm for an unrelated offence.
He appeared at High Wycombe Magistrates' Court and was remanded in custody.
Two other men, aged 23 and 25 from High Wycombe, have been arrested on suspicion of attempted murder and remanded in police custody.
A 27-year-old woman from High Wycombe who was arrested on suspicion of assisting an offender has been released while inquiries continue.