The incident happened around 12.10am when a black BMW travelling northbound on the A41 past Bourne End, towards Tring, collided with the central reservation and entered the opposite carriageway leaving the passenger with life threatening injuries.
“I am appealing to anyone who may have been in the area at the time of the collision to review their dash cameras and come forward if they have witnessed the collision or the lead up to it,” said Road Policing Sergeant Dan Cook.
“We are looking to trace another vehicle which was potentially on the A41 at the time, possibly a dark coloured vehicle.”
A 48-year-old man has been arrested on suspicion of driving offences and remains in custody at this time.
Anyone with any information or dash cam footage is asked to email [email protected]
You can report information online at https://orlo.uk/GG0Gk, speak to an operator in our Force Communications Room via our online web chat at https://orlo.uk/XIK08 or call the non-emergency number 101, quoting 41/68226/26.
Alternatively, you can stay 100% anonymous by contacting the independent charity Crimestoppers on 0800 555 111 or via their untraceable online form at crimestoppers-uk.org