A pedestrian was left with life-threatening injuries after a car smashed into a road sign which then collapsed on top of her.
The 37-year-old was walking through High Street, Wealdstone, when a black Ford Galaxy mounted the kerb and collided with the sign, which in turn struck her, causing serious head injuries.
She was taken to an east London hospital where she was described as being in a critical condition.
The man who was driving the Ford Galaxy was arrested on suspicion of causing a serious injury by dangerous driving. He remains in custody.
An investigation has now been launched. Witnesses should call 0208 991 9555.