An 11-year-old girl was killed while waiting with her mother at a bus stop when a pensioner's car veered on to the pavement and crashed into them.
Officers were called to The Common in Stanmore, following reports that a vehicle had collided with two pedestrians and a stationary bus.
Emergency services pronounced the girl dead at the scene, while her 46-year-old mother was taken to hospital and remains in a critical condition.
Firemen cut the 69-year-old driver from her Ford Fiesta and she was taken to hospital with minor injuries. No arrests have been made.
Police said they were awaiting formal identification ahead of a post-mortem due to take place tomorrow at Northwick Park Hospital.An inquest is expected to open at Barnet Coroner's Court "in due course", Scotland Yard said.
More top news
The property developer painted the mews house in March last year after she was denied permission for a basement below the property.
Profits at the estate agent plummeted 42% in the first half of the year.
Ionut Gheorghe, 27, was detained in Los Molinos near Madrid on Friday by Spanish police under a European Arrest Warrant.