Police are appealing for witnesses to a road traffic collision outside Northolt Underground Station.
Officers were called to Mandeville Road, Northolt, at 00:21hrs on Saturday, 9 March following a collision between a pedestrian and a silver Vauxhall Astra.
The pedestrian, a 22-year-old man, sustained life-threatening injuries and is currently in a critical condition in hospital.
A 23-year-old man was arrested on Saturday, 9 March on suspicion of dangerous driving and failing to stop at the scene of an accident. He has been released under investigation pending further enquiries.
Detective Sergeant Ben Massink, of the Met’s Serious Collision Investigation Unit, said: “Analysis of CCTV footage shows there were a number of people and vehicles in the area at the time of the collision and I would like them to come forward and contact police.
Any witnesses or anyone with any information is asked to call the Serious Collision Investigation Unit, based at Alperton, on 0208 2469820.
Alternatively, information can be given anonymously by calling Crimestoppers on 0800 555 111.