The BMW was carrying four men when it crashed on Toller Lane in Bradford at around 5.30am today (Thursday).
The crash is now being investigated by the Independent Office for Police Conduct (IOPC).
They said in a statement that '"t is understood, at this time, that the car was being followed by an unmarked police car at the time of the crash."IOPC Regional Director Miranda Biddle said: “This is a most tragic incident and our sympathies are with the family and friends of those who have died. “West Yorkshire Police made a mandatory referral to the IOPC and at 6.24am we declared an independent investigation. Our investigators are attending post incident procedures, have travelled to the scene and have begun gathering evidence.”
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