Detectives are questioning two people over the death of a 12-year-old boy who was killed in a hit-and-run incident involving the police.
Bilal Raffey Khizar was on a road crossing on Rooley Lane in Bradford when he was hit by the red Seat Ibiza at around 7pm on Saturday.
The incident happened as the vehicle made off at speed after being stopped by police for a check, West Yorkshire police said.
A marked police car pulled over the Seat Ibiza in a lay-by on Rooley Lane, but as officers got out of their car to approach the vehicle, it made off at speed along the road, a force spokesman added.
Police followed the car, which collided with Bilal on a crossing close to the Asda store just moments later.
The spokesman said: "He tragically died of his injuries."
The car did not stop but continued to the Chain Bar roundabout on the M606, where it was in collision with two other vehicles.
It was later found on Westfield Lane, in the Wyke area of Bradford.
Two people were later arrested as a result of police inquiries, which were said to be at a very early stage.
The Independent Police Complaints Commission (IPCC) was contacted and an investigator attended the scene.
Detective Superintendent Mark Ridley, who is leading the investigation for West Yorkshire Police, said: "This is a tragedy for the family and they are absolutely devastated. Specially trained officers are currently working with them.
"I am appealing directly to anyone who saw the vehicle being driven or the incident to get in contact.
"I need the community to come forward and tell me what has happened and what they have seen to help bring justice to the family."
The IPCC said it had launched an investigation into the actions of the police officers before the fatal collision.
A spokesman said the investigation will examine the stopping of the Seat Ibiza, the interaction between officers and the people in the car and the following attempted police pursuit.
He said officers attempted to chase the Seat after it drove off from the lay-by but lost sight of the car.
The spokesman said: "West Yorkshire Police notified the IPCC of the incident and an IPCC investigator was immediately deployed to begin an assessment."
He continued: "The IPCC has deployed additional investigators this morning to begin an independent investigation which will examine the initial stop of the Seat Ibiza by officers, their interaction with the occupants and the ensuing attempted police pursuit."
Any witnesses are asked to contact police on 101 or Crimestoppers on 0800 555111.