The teenager was travelling with her mother, father and brother in Ilderton Road, New Cross, south London on Sunday when their Volkswagen Polo and a Peugeot 308 that was being chased by a marked police car collided.
The girl, who was in the rear of the car, died at the scene from her injuries, Scotland Yard said. Police later said the collision occurred between New Cross and South Bermondsey, in the borough of Southwark.
Her parents and brother were taken to hospital and their injuries were not thought to be serious.
The male driver of the Peugeot was arrested and taken into custody.
A female passenger was taken to hospital suffering from minor injuries.
The incident happened just before 6.30pm and police, ambulance and fire crews attended.
The Metropolitan Police said the pursuing police car had its blue lights and sirens on when the collision happened.
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.
I have very real concerns that this loss of life, should not have been lost.
This road is main entrance to Millwall football ground, so police could have closed off the road at each end fast.
This road was also very busy Sunday with the huge numbers of people coming from the large number of Churches in the area., i was delivering the new People Before profit news letter in this part of New Cross on Sunday.