This harrowing dashcam footage shows a lorry driver changing music on his mobile phone just moments before killing a mum and her three kids in a horror crash.
Tomasz Kroker was distracted for just seven seconds in the moments leading up to the eight-vehicle smash on the A34 in Berkshire two months ago.
The tragedy claimed the lives of Tracey Houghton, 45, as well as her sons, Ethan, 13, and Josh, 11, and her step-daughter, Aimee Goldsmith, 11.
Today, shocking footage emerged of the seconds before the deadly crash on August 10, as Kroker was jailed for 10 years at Reading Crown Court.
The video, recorded on the 30-year-old Polish driver's dashcam, shows him scrolling through music on his phone as he sits behind the wheel of his vehicle.
It is only 0.75 seconds before the tragedy that he looks up and, with horror, realises that he is about to smash into a line of stationary traffic in front of him.
The footage was released by Thames Valley Police today in a bid to highlight the potentially catastrophic consequences of using a mobile phone whilst driving
In it, Kroker can be seen looking shocked as he strikes Tracey's car, causing a deafening noise.
The impact of the crash shunted the car underneath the back of a heavy goods vehicle, where it was crushed to a third of its size.
The mum, Ethan, Josh and Aimee, all from Dunstable, Bedfordshire, were immediately killed.
Tracey's partner and Aimee's dad, Mark Goldsmith, watched the disaster unfold as he travelled back from the family's camping holiday in another vehicle.
Earlier this month, Kroker pleaded guilty to all the charges against him. And this morning, he was locked up for a decade by a judge.
During the crash on August 10, Kroker smashed into Tracey's vehicle at 50mph as the family travelled back from the south west in a two-car convoy.
While looking at his phone, he had failed to see the line of traffic ahead of him, which had built up after another lorry slowed down while struggling to climb a hill.
Today, the prosecution showed the court the dashcam footage of Kroker using his phone, as well as pictures of the shocking aftermath of the disaster.
Some family and friends wept in the public gallery as the images were shown. Others left before the most serious pictures and footage was displayed.
Charles Ward-Jackson, prosecuting, said of dad-of-one Kroker: "He started working for a firm driving heavy goods vehicles.
"On regular routes he was driving from Andover so the Crown would say he was familiar with the road.
"On the day he reported for work at about 4pm and was assigned a white Mercedes unit attached to a long trailer. The trailer was empty.
Family's statement
In a statement read on behalf of the family today, Aimee's mother, Kate Goldsmith, said:
"Today Tomasz Kroker has been sentenced for killing much-loved members of our family. However, in our eyes, the sentence does not do justice to the crime committed. Tracey Houghton, her two sons, Ethan and Josh, and Aimee Goldsmith were innocent victims of his actions.
"On the 10th of August 2016, Mr Kroker made the decision to change his music on his phone whilst driving a lorry at 50mph. His lorry hit a queue of stationary traffic, killing four family members and seriously injuring another driver.
"In the moment Mr Kroker chose to look at his phone he caused a multiple-vehicle accident that endangered all surrounding road users and took the lives of Tracey, Ethan, Josh and my daughter Aimee.
"To all intents and purposes, Mr Kroker's use of his mobile phone whilst driving turned his lorry into a lethal weapon. He was so distracted he made no attempt to slow down."
"Before he started driving the defendant was required to fill out a driver's declaration form.
"It included: 'I will never use a mobile phone or hands-free kit while driving.' That was signed and dated by him.
"The weather was fine and traffic was running smoothly. The defendant would have had an excellent view of the road ahead."
He added: "Had the defendant been looking he would have seen a procession of vehicles slowly moving up the in the distance.
"The defendant, it is clear, was not looking. It is only 0.75 seconds before the crash that the camera shows the defendant looking up with some horror on his face."
The photos shown to the court featured the wreckage left of many vehicles after the collision, which was also witnessed by Mark's 13-year-old son.
Horrifically, some of the cars had been almost completely destroyed.
The court was also shown footage from two cameras in Kroker's lorry, which captured the tragic moments before and during impact.
The first camera showed the vehicle approaching the stationary vehicles in front of it, before ploughing into Tracy's car at high speed.
The second, meanwhile, captured Kroker looking down at his mobile phone as he held it out to the side of him with his left hand.
He could be seen scrolling through different music options while pop music played loudly in his cab, just seconds before the crash.
Looking up in shock at the very last moment, he was filmed grabbing the steering wheel with both hands and bracing for impact.
But it was far too late.
In addition to the deaths of Tracey, Ethan, Josh and Aimee, a man was seriously injured and four other people were hurt in the disaster.
Kroker - who had himself become a dad five months before the tragedy - was jailed for 10 years today by Judge Maura McGowan.
He had previously pleaded guilty to four deaths by dangerous driving and a single count of causing serious injury by dangerous driving.
Sentencing the defendant, from Hampshire, the judge said his attention had been so poor that he 'might as well have had his eyes closed'.
Speaking after the hearing, the victims' relatives released a statement, saying they felt Kroker's sentence 'does not do justice to the crime committed'.
In the statement, read on behalf of the family, Aimee's mother, Kate Goldsmith, added: "In the moment Mr Kroker chose to look at his phone he caused a multiple-vehicle accident that endangered all surrounding road users and took the lives of Tracey, Ethan, Josh and my daughter Aimee.
"To all intents and purposes, Mr Kroker's use of his mobile phone whilst driving turned his lorry into a lethal weapon. He was so distracted he made no attempt to slow down."