Four people were taken to hospital after a car ploughed into a vehicle that had overturned on the A41.
The late night smash happened between the Tring and Aylesbury exits on the bypass just before 11.30pm last night.
Two men, who were travelling in a red Lexus that had overturned, were taken to Oxford’s John Radcliffe Hospital, while the male driver of a blue Citroen Saxo and his female passenger were taken to Stoke Mandeville Hospital in Aylesbury.
The road was closed until just before 5.30 this morning.
Witnesses are asked to contact Thames Valley Police on the non-emergency number 101.