Witness appeal for three vehicle collision on the M1
The collision involving three vehicles, a black Lexus IS200, a white DAF HGV and a white MAN HGV, happened at 1.07am on the northbound carriageway, approximately 600 metres away from the junction 12 slip road.
Both drivers of the HGV vehicles were not injured, the driver of the Lexus was taken to Luton and Dunstable Hospital for treatment to minor injuries.
The front seat passenger in the Lexus suffered a serious head injury and was taken to the Luton and Dunstable Hospital, she has been transferred to Addenbrookes Hospital and is in a serious condition.
PC Robert Hauxwell, investigating the collision, is keen to trace motorists who were in the area when it happened and may be able to piece together exactly what happened.
Police closed all four lanes but part of the road was reopened at 9am.
Call 101 with information.