Detectives from the Roads and Transport Policing Command are appealing for information and witnesses following a fatal collision in Bromley.
Police were called by London Ambulance Service to Main Road junction with St Winifred's Road, TN16 at 02:35hrs on Wednesday, 11 October following reports of a road traffic collision.
Officers attended and found two cars in collision with each other in a bush.
London Air Ambulance landed at the scene.
Four injured people were found. A 74-year-old woman was found suffering critical injuries and died at the scene. Her next of kin have been informed.
A post-mortem examination will be held in due course. Formal identification awaits.
A man ages in his seventies - who was in the same car as the fatally injured woman - has been taken to hospital with a broken leg. Another woman from the same car was treated for minor injuries.
No pedestrians were injured in this collision.
A 17-year-old male - the driver of the other car involved - was arrested at the scene on suspicion of causing death by dangerous driving. He will be taken to a hospital for assessment before being taken to a south London police station for questioning.
Enquiries continue. Local road closures are in place and motorists are advised to avoid the area.
Officers from the Serious Collision Investigation Unit continue to deal.
Any witnesses or anyone with any information is asked to call detectives on 0208 285 1574 or contact via Twitter @MetCC.
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org