Commander Tony Eastaugh said:
An innocent family are now dealing with the tragic loss of a loved one.
The Metropolitan Police has now begun a thorough investigation into the circumstances of this terrible incident.
The thoughts of our staff and officers are with the family at this time.
Traffic police and officers from the Directorate of Professional Standards are now investigating, the force said.
The Independent Police Complaints Commission has also been informed and an investigator was at the scene assessing the circumstances of the collision.
More top news
One week on from the Westminster terror attack a vigil is to be held on Westminster Bridge to remember the victims killed by Khalid Masood.
A man who was paralysed in a cycling accident can now move his right arm and hand thanks to thought-controlled technology.
Square, the payment service which enables small businesses to take card and contactless payments, has launched in the UK.