The victims, all in their late teens and early twenties, were declared dead at the scene of the accident on the A422 Brackley Road, Westbury, Buckinghamshire.

A fifth person was airlifted to a hospital in Oxford and remains in a critical condition.

The incident is not thought to have involved any other vehicle, said a spokesman for Thames Valley Police.

He added that formal identification of the victims has not yet taken place.

The road was closed for several hours to allow access to emergency services and collision investigators.

Staff at the BP filling garage in Brackley, Northamptonshire, said that the crash happened between Brackley and Buckingham close to the turning for Mixbury, Oxfordshire.