An on-duty plain clothes officer tried to stop a car that crashed into him in a hit-and-run collision which police are now treating as attempted murder.
The 30-year-old police constable was taken to hospital with head injuries from the collision, which took place just after 3.15pm on Tuesday in Market Square, Aylesbury, Thames Valley Police said.
The officer tried to stop the red Vauxhall Astra, but it drove off and was involved in two other collisions before it was abandoned in nearby Osier Way.
The driver and two passengers, all believed to be male, fled the scene, a force spokesman said.
The officer, who is based in the town, was discharged from hospital on Tuesday night. He has concussion and is recovering at home. No-one was injured in the other crashes.
Investigating officer Detective Inspector James Mather said: “I am appealing to anyone who may have information about the incident to please contact police immediately.
“I would particularly like to speak to anyone who has mobile phone or dashcam footage of the incident or the vehicle being driven in the town to come forward.
“I would also like to hear from anyone who saw a vehicle matching the description being driven erratically in the town.
“Thankfully the officer is now recovering at home with support from his family and the force. This incident highlights the sacrifices that police officers and staff make every day to protect the public across the country.”
Anyone with information should call police on 101 quoting (13/2).