Grieving police officers are working 20-hour shifts as they investigate a crash and a fire which left nine people dead, a Police Federation representative has said.

Seven people, including PC Matthew Blades and PC Tom Clough, died in the crash near Middlesbrough on Saturday, followed by a house fire in Grangetown on Wednesday that claimed the lives of a woman and a seven-year-old girl.

Cleveland Police Federation chair Lauren Somerville told BBC Radio Tees it had been "more intense than ever in amongst pain and grief", as an extra 200 police officers are being sent to help.

"It's been unimaginable... those feelings are going to continue for days, weeks, months and years," she said.

Somerville said the extra officers would be used "wherever is needed".

"It's a testament to Tom and Matthew's memory that the whole country is behind us," she said.

"It's a real sense of people starting to understand what the sacrifice of policing is."

On Saturday, PC Blades and PC Clough died when a Volkswagen Passat, which was going the wrong way on the A66 at South Bank, hit their vehicle.

The five young men in the Volkswagen also died and inquests into all seven deaths opened on Thursday.

Police said 17 people, aged between 18 and 61, had been arrested across Teesside as part of an investigation into the lead-up to the crash.

They have been held on a range of offences including possession of a firearm and being part of an organised crime group.

On Wednesday, Natalie McDonald, 34, died along with her seven-year-old niece Valentina Foster in the fire in Grangetown.

Natalie's mother, Lisa Kirton, described her as "a beautiful soul, who would have done anything for anybody".

Valentina, who was known as Tina, was staying at the house for the summer holidays and had been "dancing around the living room" only the previous night.

A fundraiser for the two police officers set up by the Cleveland Police Federation topped £1m earlier this week.

Somerville said: "It's felt really difficult and to see that many people supporting us and speaking about us and wrapping their arms around Cleveland - it's helping us through."

Leader of Redcar and Cleveland Council Alec Brown said people were frightened and the council's "fundamental" priority was for them to feel safe in their homes.

He said the area had been "inundated" with national press.

"Every incident that happens is getting in the media and on social media and that heightens awareness of everything that's going on and feeds into people not feeling safe in their homes," he added.

On Thursday evening videos shared on social media appeared to show several cars on fire at a vigil in Haswell, County Durham, where balloons were released in tribute to one of the men killed in the A66 crash.

The BBC has contacted police and the fire service.

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