A man, 30, and an 18-month-old girl are fighting for their lives in John Radcliffe Hospital following the ‘horrendous incident’, which happened on the A40, near Oxford, at around 9.50pm last night.
The children, aged four, six and eight, and a 29-year-old woman are members of the same family from Chinnor, Oxfordshire.
The collision involved a people carrier and a heavy goods vehicle on the A40 near Oxford last night, Thames Valley Police said.
Two other passengers in the Subaru people carrier, a man, 30, and an 18-month-old girl, are fighting for their lives.
They were taken to the John Radcliffe Hospital in Oxford after the smash, which took place near a railway overbridge at around 9.50pm.
The 56-year-old man driving the heavy goods vehicle suff guyered minor injuries in the crash.
Eyewitness David Patchett, who lives nearby, called the emergency services after seeing several people seriously injured.
He told the Oxford Mail: “I was first on scene and I am still shaky now. I need my mind to rest.”
Two girls aged four and eight, a six-year-old boy and a woman, 29, were pronounced dead at the scene.
Senior Investigating Officer Sergeant Dominic Mahon, of Thames Valley Police, appeal to the public and media not to speculate as to the cause of the horrendous incident.
“This is an absolute tragedy, and I would ask the public and the media not to speculate as to the cause, as we continue to support the families of all of the victims”.
Sgt Mahon added that the family’s next of kin had been informed and were being supported by Family Liaison Officers and urged anyone who was in the area or has dashcam footage of the incident – or vehicles involved – to get in touch with them.