A 16-year-old boy is among five more people arrested by detectives investigating events leading up to a crash on the A66 that killed two police officers and five others.
It brings the total number of arrests to 17 following the fatal crash near Middlesbrough in the early hours of Saturday.
PC Matthew Blades, 37, and PC Tom Clough, 38, were killed when a Volkswagen Passat, which had been pursued by police, was driven the wrong way along a dual carriageway and hit their marked armed-response vehicle.
Cleveland Police say they have now arrested five more people with the help of the National Crime Agency and the North East Regional Organised Crime Unit.
The force said those arrested were a boy aged 16, an 18-year-old and a man of 21, all on suspicion of participating in an organised crime group; a 23-year-old on suspicion of making threats to kill and a 55-year-old on suspicion of assisting an offender.
Cleveland Police said two of the 12 people previously arrested have already appeared in court.
Kai Beattie, 19, of Foxrush Court, Redcar, appeared before Teesside Magistrates’ Court charged with possession of a firearm with intent to endanger life, according to the force.
open image in galleryCameron George, 26, of Micklow Close, Redcar, was remanded in custody to appear at Teesside Crown Court on September 21 charged with drugs offences and possession of criminal property, it said.
Police have previously said that the five young men in the Passat may have had links to “serious and organised criminal activity”.
Four of the five young men in the car had previous criminal convictions, and were believed to be associated with another car which was seen ramming properties earlier that morning.
Pc Matthew Blades, 37, and Pc Tom Clough, 38, were killed when the Passat, which had been pursued by police, was driven the wrong way along the dual-carriageway and hit their marked armed response vehicle.
The five people in the Passat, Cole Robert Worthy, 17, Theo Rae, 17, Makai Saddington, 18, and 23-year-olds Michael Robert Cahill and Jacob Matusiak, were pronounced dead at the scene at South Bank, early on Saturday.
Inquests were due to open on Thursday morning for the two officers with hearing for the young men in the Passat were scheduled for the afternoon at Teesside Magistrates’ Court.
Cleveland Police has previously said that on the morning of the collision, it received several reports of two vehicles being driven dangerously.
The first vehicle, believed to be a Volvo XC60, was witnessed ramming properties in the Middlesbrough area.
open image in galleryThe second vehicle, a Volkswagen Passat, is believed to have been associated with the activities of the Volvo.
Police said both vehicles were operating with cloned number plates but were picked up by automated number plate recognition technology.
The Volvo XC60 involved in the initial reports has been traced and recovered in Middlesbrough.
Police said there was no evidence that filming of the activities on Friday night and Saturday morning was “for the purposes of TikTok”.
Assistant Chief Constable Wayne Fox, responsible for the strategic leadership of the investigation, said: “This has been a fast-moving and complex investigation, with significant links to serious and organised criminal activity.”
He went on to say: “We have a duty to respond to, and thoroughly investigate, the serious criminal activity that resulted in this fatal incident, and to bring all those responsible to justice.”
More than £750,000 has been raised for the families of the two police officers who were killed.
A fundraiser created by the Cleveland Police Federation said funds raised would be split equally between the two officers’ families and the federation would continue to provide support.
Cleveland Police launched the chase after receiving intelligence relating to “numerous incidents” linked to a Passat, which activated an ANPR camera and is believed to have been using cloned plates, investigating watchdog the Independent Office for Police Conduct said.
open image in galleryPc Blades and Pc Clough were not involved in the original pursuit, but had been called to the area to assist with the search for the Passat.
Family members described former Civil Nuclear Constabulary officer Pc Clough as “our hero” who was “always on public duty”.
In a statement issued by Cleveland Police, Pc Blades’ wife called him “my beloved husband, my best friend, and the most devoted father to our two young boys”.
Tributes for the five young men were also shared on social media, with many of their friends saying they “can’t believe it” and were “heartbroken” and “lost for words”.
Balloon releases have been announced in their memory at different locations.
Meanwhile, Paul Williams, acting deputy national chairman for the Police Federation of England and Wales, appeared on BBC Breakfast on Tuesday morning as he claimed young people are “baiting police officers” with dangerous driving.
Williams said: “Every day we can identify now numerous examples of young people sensationalising dangerous driving.
“Not just dangerous driving, but baiting police officers who are out there to protect the public. It’s a real problem. It’s causing officers concern.
“They shouldn’t have to be going out and worrying about whether they’re going to return home from their shift or not. But on top of that, wondering if they’re going to be plastered all over social media.
“It’s absolutely unacceptable and social media platforms need to take some action.”