A woman died in the early hours of Christmas Day after a car crashed in Edgware shortly after being told to stop by police.
At roughly 3.45am officers in a marked police car told the vehicle to stop on Hendon Way - but it made off and there was no pursuit.
A short time later, Scotland Yard says, police were informed of a crash involving the same car, another vehicle and a lamppost at the Brent Cross Flyover.
The occupants of the car that did not stop for police fled the scene on foot.
The passenger of the second car, a 22-year-old woman, suffered serious injuries and was declared dead at the scene.
Road closures remain in place while the scene is dealt with.
A 29-year-old man was subsequently arrested on suspicion of causing death by dangerous driving and is in custody. Enquiries are ongoing to trace other occupants of the car.
The woman’s next of kin have been informed. Anyone with information that could assist police, including any road users with dash cam footage, is asked to call 101 or tweet @MetCC and quote CAD933/25Dec. Alternatively, contact the independent charity Crimestoppers anonymously on 0800 555 111.