A lorry driver has admitted killing three children and a mother while distracted by his mobile phone in a "devastating" crash, Thames Valley police have said.
Tomasz Kroker, 30, from Trajan Walk, Andover, Hampshire, drove into stationary traffic at an estimated 50mph.
Tracey Houghton, 45, from Bedfordshire, Josh Houghton, 11, Ethan Houghton,13, and Aimee Goldsmith, 11, all died at the scene.
Five others were injured in the crash which happened shortly after 5.10pm on August 10.
Kroker pleaded guilty to four counts of causing death by dangerous driving and one count of causing serious injury by dangerous driving at Reading Crown Court on Monday, the Crown Prosecution Service said.
He will be sentenced on October 31.
The collision happened on the A34 between East and West Ilsley junctions in Berkshire, police added.
Detective Sergeant Gavin Collier, from Serious Injury Collision Unit, said: "This was a truly devastating case where a mother and three children lost their lives and a man was seriously injured.
"The most tragic element of this incident is that it was avoidable. Tomasz Kroker was looking at his mobile phone while driving, this needless and avoidable act has resulted in the most devastating circumstances."