Three men were taken to hospital last night after a two-car pile-up on the Aston Clinton bypass.
The injured men had to be freed from their vehicles by firefighters, who were called at 11.13pm.
Two of the men, who were in a red Lexus IS200, were taken to Oxford’s John Radcliffe Hospital with serious injuries.
The other man, who was in a blue Citroën Saxo with a woman, was taken to Stoke Mandeville Hospital with suspected broken bones.
The woman, who had minor injuries, managed to get out of her car before fire crews arrived.
Three fire crews from Aylesbury and one from Amersham attended the incident, which happened on the northbound carriageway near the Tring turn off.
One of the cars had flipped onto its roof during the incident and the ambulance service sent five crews to treat the injured people.
The road was closed until 5.21am and traffic diverted while emergency services dealt with the incident.