Thames Valley Police is appealing for witnesses following a fatal collision in Milton Keynes.
At around 10.20pm on December 14 two cars, a BMW and a Hyundai, which were travelling in Stratford Road, Wolverton, were involved in a collision.
A man who was a passenger in the BMW died of his injuries at the scene.
Three further occupants of the BMW, a woman and two men were taken to the John Radcliffe Hospital in Oxford.
The woman subsequently died in hospital yesterday (December 15).
The two men, one of whom was the driver, remain in hospital in a serious but stable condition.
A man, who was also a passenger in the BMW, was airlifted to Addenbrooke’s Hospital in Cambridge where he remains and is currently in a critical condition.
The occupants of the Hyundai, a man and a woman, received minor injuries and were taken to Milton Keynes General Hospital, from where they were subsequently discharged.
The road was closed while roads policing officers attended the scene and carried out an investigation.
Investigating officer PC Sandra Terry, said: “Officers would like to hear from anyone who witnessed the collision in which two people sadly died, or anyone who has any information about the collision, even if you think it may be insignificant, please come forward with details.
“The easiest way to do this is to contact us by calling the non emergency number 101 or you can visit your nearest police station.”
Anyone with any information about the collision should contact the 24-hour Thames Valley Police enquiry centre on 101 quoting URN 1639.