Three children were killed alongside their mother in a horror crash involving eight vehicles on the A34 near Oxford on Wednesday, August 10
Tracy Houghton, 45, was travelling with her two sons - Ethan, 13, and Josh, 11 - as well as her partner's daughter Aimee Goldsmith, 11, when the family's car was crushed between two HGVs, according to witnesses.
Aimee's father Mark Goldsmith was following in the car behind and saw the fatal crash. George Maguire 70, a distant relative of Mr Goldsmith, said:
"The family are all just heartbroken. Mark saw everything. He was travelling in the car behind."
Investigators worked through the night to gather evidence and remove the wreckage from the northbound carriageway of the A34, at East Ilsley, as tributes today poured in for the family, from Dunstable, Bedfordshire.
A school friend of one of the children said: "Today one of the most horrible things happened. One of the most innocent and nicest boys I know got killed in a car crash on the A34 along with his brother, sister and their mum. All gone, took too soon."
Another school friend of the boys added: "R.I.P. I have known you since year 5 you were such a good friend and now you are truly missed by all rest in perfect paradise."
The family of four were pronounced dead at the scene and a fifth man airlifted to hospital was in a serious condition. Medics treated nine people at the scene for minor injuries and a man and teenage boy were taken to Royal Berkshire Hospital. They have since been discharged.
Chief Inspector Henry Parsons, from Thames Valley Police, said: "Can I ask anyone who witnessed the collision, including anyone travelling on the southbound carriageway who saw anything they believe is significant, to contact police."
A spokesman for Thames Valley Police said: "A 30-year-old man from Andover was arrested on suspicion of causing death by dangerous driving and has been bailed until October 5.