West Yorkshire Police’s Det Chief Insp Jim Griffiths, who is leading the investigation into the crash, said it was believed all of the victims were travelling in the stolen Renault Clio that came off Stonegate Road in Meanwood and hit a tree shortly before 10pm on Saturday.
The Clio was stolen in the Headingley area at about 6.30pm on Saturday, police also revealed.
One of the 15-year-old boys arrested on suspicion of causing death by dangerous driving following the incident has now been released under investigation. The other remains under arrest.
Police also confirmed the stolen Clio was black in colour with the registration FL06 MWU.
DCI Griffiths said: “We are continuing to carry out enquiries to establish the full circumstances of the collision itself and the circumstances surrounding it.
“At this stage we believe that all those involved were travelling in the Clio at the time of the collision and that it was the only vehicle involved.
“We are particularly keen to hear from anyone who has seen the Clio and the manner of its driving in the time leading up to the collision.
“That vehicle was stolen in the Headingley area at about 6.30pm that day and is believed to have been driven around the Leeds area during that time.
“We would be interested in anyone who has dashcam footage relating to the vehicle’s movements.”
Ellis and Elliott Thornton, aged 12 and 15, died in Saturday’s crash.
They were named locally along with 15-year-old Darnell Harte, Anthoney Armour, 24, and Robbie Meerun, also 24.
Supt Matt Davison, who heads neighbourhood policing for the Leeds District, said: “This is a very tragic set of circumstances and our thoughts and condolences go out to everyone who has been affected by it.
“We are working to support the families involved and the wider community, particularly the schools who have been affected.
“We are working with the local authority and through our Safer Schools Partnership officers to support the schools at what is a very difficult time.
“Clearly the families have suffered a devastating loss and we appreciate that emotions will be running high in the community.
“We would ask that people focus on supporting each other and on supporting the police investigation which will ensure that the circumstances of this incident are fully explored and that the criminal justice process is satisfied.”