A 15-year-old boy has been arrested on suspicion of causing death by dangerous driving after three men died when a van went the wrong way on to a motorway and crashed head-on with a taxi.
It happened on the M606 near Chain Bar roundabout in Bradford, West Yorkshire, at around 10.45pm on Monday.
West Yorkshire Police referred itself to the Independent Office for Police Conduct (IOPC) as one of its vehicles was in the vicinity before the Ford Transit van, believed to have been stolen, headed the wrong way off a roundabout and on to the motorway.
Those killed were the 28-year-old taxi driver, his customer, aged 49, both of whom died at the scene, and an 18-year-old passenger in the van who was treated in hospital but died of his injuries.
A 17-year-old in the van remained in hospital with serious but not life-threatening injuries, the force said.
The 15-year-old driver was arrested on suspicion of causing death by dangerous driving but remained in hospital with serious but not life-threatening injuries.
The IOPC sent investigators to the scene and said evidence indicated the police did not follow the van the wrong way on to the motorway.
IOPC regional director Thea Walton said: “This was a tragic incident that has resulted in three people losing their lives. Our thoughts are with all those affected.
“We understand this will have caused considerable concern in the community and I would like to reassure people that there will be a thorough, independent investigation to understand exactly what has happened.
“We will be in contact with the families as soon as possible to explain our role and how our inquiries will progress.”