Specialist collision investigators are appealing for witnesses to a double fatal collision near Latchmere Leisure Centre.
Police were called by London Ambulance Service (LAS) to Latchmere Road at 03.26hrs on Saturday, 16 July to reports of a Mini Cooper on its roof.
At this early stage in the investigation, detectives do not believe any other vehicles were involved in this collision.
Officers attended along with London Ambulance Service and London Fire Brigade.
Despite the efforts of emergency services, two passengers – a man and a woman – were pronounced dead at the scene.
The driver and another passenger remain in hospital and their injuries are not life-threatening.
The driver, a 22-year-old woman, was subsequently arrested on suspicion of causing death by dangerous driving.
Extensive road closures remain in place as the investigation continues.
Detectives are keen to hear from anyone who may have witnessed the collision or have dashcam footage of the incident.
Anyone with any information is asked to call the Serious collision Investigation unit on 020 8991 9555 and give reference 1112/16July.