Two people were taken to hospital with serious injuries and a third suffered minor injures when two cars collided in Brighouse on Sunday night.
West Yorkshire Police yesterday said it had referred the incident to the Independent Police Complaints Commission (IPCC) as it appealed for witnesses.
A blue Ford Kuga had been travelling along Elland Road towards Elland when it was involved in a collision a silver Mazda Premacy at about 6.45pm.
The incident happened close to the junction with Cromwell Bottom Drive.
The driver of the Mazda, a 49-year-old man from Halifax, was taken to hospital with serious injuries. A 27-year-old woman, who was a passenger in the car, was also seriously injured.
The 58-year-old woman driver of the Kuga suffered minor injuries.
A police spokesman said: “Shortly before the incident a police patrol had seen the Mazda and was looking to stop it in relation to a burglary investigation and theft of a car in the Holywell Green area of Halifax. That incident happened between 10am and 2pm on Sunday.
“Because of this incident the collision was referred to the (IPCC), to oversee the investigation into the collision in line with National policy.”
Anyone who witnessed the collision or the movements of the vehicle prior to it is asked to contact the Safer Roads and Neighbourhood Support team on 101, quoting log 80739 of 28 August.