A young woman has been flown to hospital with serious injuries after she was hit by a mini-bus.
The pedestrian, a 19-year-old woman, was taken by air ambulance to the John Radcliffe Hospital and police are appealing for information.
The crash, just after 3pm, shut the A418 Oxford Road in both directions and caused traffic chaos throughout town.
Emergency services worked at the scene for more than an hour but the road has since been reopened in both directions.
Investigating officer, Sgt Dan Collett of the Roads Policing Unit based, said: “This collision has taken place outside the Sir Henry Floyd Grammar School at a time when pupils were starting to leave school.
“I would appeal for anybody who witnessed the collision to please make contact with us to help with our enquiries.
“It has been brought to our attention that some members of the public may have recorded events after the collision on their phones.
“I would urge them not to share the footage or post it on social media to avoid any further upset to the injured pedestrian’s family.
“If you have any information in relation to this collision can contact PC Mike Sapwell from the Roads Policing Unit at Milton Keynes on 101 or alternatively through CrimeStoppers on 0800 555111.”