Seven people including two police officers were killed in a crash on the A66 on Saturday
Police abandoned the pursuit of a car seconds before it crashed going the wrong way down a dual carriageway, killing all five men aboard and two officers, investigators have said.
Michael Robert Cahill, 23, Jacob Matusiak, 23, Theo Rae, 17, Makai Saddington, 18, and Cole Robert Worthy, 17, died when a Volkswagen Passat struck a Cleveland Police vehicle on Saturday on the A66 near Middlesbrough.
PC Matthew Blades, 37, and PC Tom Clough, 38, who were on the correct side of the road and were helping search for the car, were also killed.
The Independent Office for Police Conduct (IOPC) said the force had been pursuing the Passat following reports of "numerous incidents" linked to it.
The watchdog, which launched an immediate investigation, said the Passat was believed to be using cloned registration plates which activated an ANPR camera.
Analysis of footage from one of the police vehicles showed the pursuit lasted just under seven minutes before the Passat travelled on to the wrong side of the A66, at which point officers "abandoned" it, the IOPC said.
The pursuing officers continued to travel on the correct side of the carriageway but approximately 10 seconds later at about 03:39 BST, the Passat collided with the vehicle of PC Blades and PC Clough, who were "in the area to assist in a search" for the car, a spokesman said.
Security footage from a house on Lime Road in Middlesbrough appears to show a car being pursued by police vehicles three minutes before the crash.
Watch: Video appears to show police pursuit minutes before fatal crash
Chief Constable Victoria Fuller said on Saturday it was an "incredibly sad day for Cleveland", adding: "No one should leave their home and not return safely."
Fuller said she and her deputy chief constable visited the officers' families to "offer our condolences, support one another, and begin to come to terms with this unimaginable loss".
Politicians, including the prime minister and home secretary, have remembered the officers, with Andy Burnham saying he was "devastated" by the news.
The Great North Air Ambulance said it "will be felt across our communities and among all those who responded and supported the emergency response".
The five killed were Jacob Matusiak, Makai Saddington, Theo Ray, Michael Robert Cahill and Cole Robert Worthy
Anna Turley, MP for the Redcar constituency where the crash happened, said it was "devastating" to think about the grief of the families involved.
"There were seven lives cut short needlessly in the early hours of yesterday morning and that's a tragedy for the community here, it's a tragedy for the Cleveland Police family. Everybody today is really mourning the loss of those lives."
She paid tribute to the "bravery" of PC Blades and PC Clough and said "no one should not come home to their families at the end of their shift."
Cleveland Police Federation chairwoman Lauren Somerville said the loss of the officers was "unfathomable", adding: "Words cannot describe the pain the Cleveland Police family are feeling today."
Watch: Cleveland Police names the two officers who died in crash near Middlesbrough
When someone dies following police contact, it is mandatory for the case to be referred to the IOPC.
IOPC Director of Engagement Derrick Campbell said the watchdog recognised the "devastating impact" the incident had had on the force and "wider policing community".
He said: "We have obtained initial accounts of officers involved in the pursuit, the incident log and in-car footage of the incident.
"Work is ongoing to obtain additional material.
"IOPC investigators will continue to review and analyse all the evidence available to us."
The A66 is the major artery through Teesside
Cleveland Police and Crime Commissioner Matt Storey said it was important to let the IOPC do its investigation.
"I would advise anybody who has opinions or hearing things on social media to make sure that misinformation doesn't spread and we let the IOPC do its work," he said.
PC Blades, a married father of two, had recently become a coach at Seaton Carew FC and was preparing for his first season teaching its under-sevens Seahawks squad, the club said.
The officer and his family were "much-loved members of our club and football family", it added.
The A66 - the major artery through Teesside - remained closed on Sunday with the location of the crash surrounded by industrial units and factories.