An eight-year-old boy was killed after a pile-up involving seven vehicles on the A14.
The road was closed in both directions for several hours after the crash, leading to long delays.
The accident happened near Quy in Cambridgeshire on Friday afternoon and police said one of the vehicles involved was a car towing a caravan.
The road was closed in both directions for several hours after the crash, leading to long delays.
The boy, travelling with his family from Thrapston in Northamptonshire, was in the rear of the car.
The 38-year-old driver was hurt, a 38-year-old woman treated for shock and a boy and girl suffered minor injuries.
The driver, the woman and a boy aged six and a girl aged three were taken to Addenbrooke's Hospital in Cambridge for treatment, a police spokesman said.
A 60-year-old lorry driver from Stowmarket and a 19-year-old passenger from Ipswich in a van involved in the crash were also treated in hospital for their injuries.
Three lorries, two cars and a van were involved in the crash as well as the vehicle towing the caravan.
Cambridgeshire Police have opened the road to traffic and have started an investigation into the incident.