Detectives believe a boy left fighting for his life in a hit and run was deliberately targeted.
Officers were called to the junction of Poplar High Street and Bazely Street in Poplar at 6.59pm on Monday, September 9, following reports of a collision.
Det Sgt Lauren Brady said: "This is being treated as a grievous bodily harm with intent investigation.
"We believe the victim was deliberately targeted and was dragged a significant distance underneath the vehicle."
Officers and paramedics attending the scene found a maroon Ford Focus and the 17-year old.
A Met spokeswoman said: "The victim was rushed to hospital, initially in a critical condition. He injuries have now been assessed as life-changing."
The driver of the car involved in the collision fled the scene and efforts to trace them are continuing.
No arrests have been made.
Det Sgt Brady said: "I know there were a number of witnesses and anyone who hasn't contacted police, or people with any dash-cam footage, are asked to call police via 101 quoting reference Cad 6546/09Sep.
"Alternatively, call Crimestoppers anonymously on 0800 555 111."
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