Officers are keen to speak to anyone who saw a Ford Transit van driving on Bradford Road in the vicinity of Moorlands Road, Birkenshaw shortly before it was involved in a collision with a taxi at 10.45pm on June 13.
The taxi driver and passenger died at the scene.
Police can now officially name them as Sohail Ali, 28, of Bradford and Simon McHugh, 49, of Huddersfield.
Kyden Leadbeater, 18, from Bradford, who was a passenger in the Ford Transit van, died in hospital.
The other passenger in the van, a 17 year old male, has been discharged from hospital and was arrested and interviewed on suspicion of causing death by dangerous driving. He has since been released on bail pending further enquiries.
The 15 year old male driver of the Ford Transit van remains in hospital under arrest on suspicion of causing death by dangerous driving.
Detective Inspector Paul Conroy, of the Major Collision Enquiry Team, said: “This is a very tragic incident where three people have lost their lives. Our thoughts are with their families at this time.
“Our investigation into the road traffic collision is ongoing and I would appeal to anyone who saw the Ford Transit van prior to the collision to come forward.
“We are keen to get any dash cam footage or any social media footage of the driving prior to the collision or the collision itself.
“Footage given to the investigation will be treated in strict confidence.
“The 15 year old arrested on suspicion of causing death by dangerous driving remains in hospital and we will look to interview him when he is fit and able.”
Anyone who has information that can help us with our investigation is asked to contact police via 101 or the live chat options at www.westyorkshire.police.uk/contactus quoting crime reference 13220319922.
West Yorkshire Police has referred itself to the Independent Office of Police Conduct.