Seven more men have been arrested as part of an operation tackling alleged organised crime after the head-on crash on the A66 that resulted in seven deaths, Cleveland police have said.

Officers said four men, aged 21, 25, 35 and 40, were being held on suspicion of criminal damage with intent to endanger life after a vehicle crashed into a house in Steele Crescent, Middlesbrough.

They were also being questioned over alleged arson after a caravan was set alight in Atlee Road on Wednesday morning, and over a drug offence.

The force said the men were in a vehicle when they were stopped by police in Kingsley Road in Grangetown on Thursday night.

Class A drugs were seized, officers confirmed.

The three other men arrested were a 23-year-old man, on suspicion of threats to kill, a 42-year-old on suspicion of threats to kill and possession of criminal property, and a 30-year-old on suspicion of possession of criminal property.

All three have been released on conditional bail.

It brings the total number of people arrested since the crash to 24.

Earlier on Friday, detectives confirmed they were not linking a house fire that killed a seven-year-old girl and her aunt to the A66 crash, which left two police officers and five young men dead.

Hundreds of extra police officers have been drafted in to support officers after a series of incidents in the Middlesbrough and County Durham area.

Inquests have been formally opened into the deaths of the seven people in the crash in the early hours of 22 August. The two police officers who died were PC Matthew Blades, 37, and PC Tom Clough, 38.

The Teesside area coroner, Paul Appleton, said that there was a collision at South Bank between a police vehicle and a Volkswagen Passat.

He said the provisional cause of death for Blades was head and neck injuries and for Clough was neck injuries.

Later, inquests were opened and adjourned into the deaths of the Passat occupants, named as Cole Worthy and Theo Rae, both 17, Makai Saddington, 18, and 23-year-olds Michael Robert Cahill and Jacob Matusiak.

Police initially arrested 17 people after the crash, which followed a police pursuit, as part of an investigation into alleged organised crime.

Cleveland police assistant chief constable Wayne Fox said of the latest arrests: “This latest disruptive activity now brings the total number of arrests to 24 since the investigation commenced.

“Several suspects arrested throughout the course of this week have been charged with serious offences and a number of offenders have been recalled to prison.”

On Friday, Cleveland police said Kai Inico, who was arrested on Monday on suspicion of participating in an organised crime group, had been charged with possession with intent to supply a class B drug.

The force said four other people arrested on Monday had been bailed – a 16-year-old boy and 18-year-old man arrested on suspicion of participating in an organised crime group, a 55-year-old man arrested on suspicion of assisting an offender, and a 23-year-old man arrested on suspicion of threats to kill.

Earlier this week, two other people were charged with offences and appeared in court.

Meanwhile, two men have been arrested on suspicion of murder in connection with the fire which killed Natalie McDonald, 34, and seven-year-old Valentina Foster, as well as injuring four others, in Grangetown.

Matt Storey, the police and crime commissioner for Cleveland, said on Friday: “After what has been the most tragic week in its history, I want to extend my heartfelt thanks to local residents for the outpouring of love and support they have shown to Cleveland police.

“My thoughts remain with the family, friends and colleagues of PC Matthew Blades and PC Tom Clough. They will be remembered as selfless, professional and courageous police officers, dedicated to serving their communities.”