A 27-year-old woman is fighting for her life in hospital after a car crash which injured three others including two children.
The A329 was closed both ways for nearly three hours following the two-car collision between Great Milton and Stadhampton shortly before 10am.
One person also had to be cut from the wreckage by firefighters.
Thames Valley Police spokeswoman Lucy Billen said the black Ford Focus and black Volkswagen Golf were travelling in opposite directions before the collision.
She said the 27-year-old woman, who was driving the Ford Focus, was in a critical condition and the driver of the Golf, a woman aged 47, and her two 12-year-old passengers were also taken to the John Radcliffe Hospital in Oxford.
South Central Ambulance Service spokeswoman Michelle Archer said paramedics were called to the crash scene at about 9.45am.
She added that the air ambulance was sent along with four ambulance crews, a rapid response vehicle and two ambulance officers.