Police are appealing for witnesses after a Ford Focus smashed into three parked cars leaving a 27-year-old man dead.
The man, who was a passenger in the blue Focus was declared dead at the scene and another passenger, aged 25, is in critical condition.
His next of kin have been informed.
The driver together with two further passengers are also in hospital but their injuries are not thought to be life threatening.
The driver has been arrested on suspicion of causing death by dangerous driving and driving without insurance.
Police were called at 3am this morning to The Mall in Harrow in north west London.
Officers, the London Ambulance Service and the London Fire Brigade all attended the scene and found the five occupants of the Ford Focus with injuries.
Detectives from the Serious Collision Investigation Unit based at Alperton are investigating.
They are appealing to anyone who may have seen the car prior to the incident or who may have witnessed the collision to contact them.
Anyone with any information is asked to call 0208 991 9555 or Crimestoppers anonymously on 0800 555 11.