The mother of a teenager among five killed in a collision after he drove the wrong way on the M4 has reportedly apologised to the victims' families.
Christopher Beresford, 18, was killed at the wheel of the Mondeo
Teresa Fielding's son Chris Beresford, 18, was driving a Ford Mondeo that had earlier been followed by police.
An Irish couple returning to their home in Surrey after a holiday were among those who died in the head-on crash on the M4 near Newport early on Monday.
Two of Mr Beresford's three companions in the Mondeo were also killed.
The only survivor of the crash, an 18-year-old man, is in a stable condition at the Royal Gwent Hospital in Newport after suffering multiple fractures.
The teenager, who has not been named, is improving and is out of intensive care, said a hospital spokesperson.
James and Bridget Stafford were travelling home after their holiday
James Stafford, 69, and his wife Bridget, 70, had been travelling on the eastbound carriageway of the M4 in their red Volvo 940 after arriving in Wales on the Rosslare to Fishguard ferry.
The Mondeo was travelling west - the opposite direction - on the same carriageway. The crash happened at 0320 BST.
They along with Mr Beresford and Lee Andrew Maggs, 26, who were both from the Duffryn area of Newport, and Sam Case, 19, from the Maindee area of the city, died.
Mother-of-four Ms Fielding reportedly told relatives: "I feel devastated for all those families.
"I had to go and identify my own child and I am sorry so many other families were put through the same thing.
"In my heart I feel I have caused the deaths of the other people who have died. I can't apologise enough."
Sam Case, 19, and Lee Maggs, 26, both died in the collision
All the evidence collected about Monday's incident, including CCTV footage and call logs, has now been handed to the Independent Police Complaints Commission (IPCC), which is investigating the crash.
IPCC commissioner for Wales Tom Davies said the organisation would prepare a report for the coroner's inquest into the cause of death.
"Our investigation will also examine the conduct of police officers and whether actions were appropriate and proportionate."
It has emerged that the Staffords had said goodbye the day before to friends and neighbours on Achill Island, on the County Mayo coast in the Irish Republic where they owned a holiday home.
A friend of the couple, Alan Gielty, who runs a pub where the Staffords stayed, said the village was "devastated" at the couple's deaths.
He said: "The whole village and probably the whole of Achill is devastated. We can't get our heads round it. We're stunned.
He added: "They didn't have any worries. James was retired, he used to come back every summer. He had a beautiful holiday home here in the village.
"He'd launch his boat at the beginning of the summer and every day, or any day that he could, he'd go fishing."
The couple's adult children live in Ireland as well as in the Croydon area of south London.
On Wednesday, the family of Lee Maggs released a statement describing him as a "very quiet and caring boy who was much loved by his family".
"We miss him so much, he was a lovely boy. We cannot believe that we won't see him again and are struggling to come to terms with what has happened."
"We feel so sad for all involved and their families and understand what a traumatic time this must be for them."
The IPCC is urging witnesses to the collision to call free phone 0800 096 9076 or e-mail firstname.lastname@example.org