Five people who died in a head-on crash on the M4 in Newport between two cars - one of which had earlier been pursued by police - have been named.
Christopher Beresford was among three men killed in the Mondeo
Christopher Beresford, 18, Lee Maggs, 26, and Sam Case, 19, from the Newport area, were in a car on the wrong side of the motorway early on Monday.
An 18-year-old man who was also in the car is critical but stable in hospital.
In the other car were Bridget Stafford, 70, and James Stafford, 69, of south London, and originally from Ireland.
The collision at 0320 BST on Monday happened minutes after Gwent Police broke off pursuit of a Ford Mondeo containing four men.
The only survivor, who has not been named, is in the Royal Gwent Hospital, Newport.
He was in the same car as Mr Beresford and Mr Maggs, who were both from the Duffryn area of Newport, and Sam Case from the Maindee area.
Their car hit the Volvo carrying the retired couple from Thornton Heath, who were originally from Achill Island, off County Mayo in the Irish Republic.
The motorway was closed in both directions for several hours
They had spent the summer in Ireland and were driving to their home after getting off the Rosslare to Fishguard ferry.
Achill priest Father Tom Kearney said: "It's a big blow to the community. James and Bridget spent their holidays on Achill every summer and had just said their goodbyes on Sunday morning."
The couple's adult children live in Ireland as well as in the Croydon area of south London.
Hours after the crash, it emerged that police had tried to stop the Mondeo at nearby Penhow but abandoned any pursuit when the vehicle turned onto the M4, in the wrong direction.
The Independent Police Complaints Commission (IPCC) is investigating the collision and has taken possession of all the evidence collected by police following the crash, including CCTV footage and call logs.
The commission said it had already received some "very useful" information following an appeal for witnesses.
Flowers have been placed on a bridge overlooking the crash scene
Tom Davies, the IPCC commissioner for Wales said when an incident occurred involving the police that involved death or serious injury by law the commission had to independently investigate the circumstances.
Mr Davies said the conduct of police officers would be examined, and a report would be prepared for the coroner's inquest into the cause of death.
"The loss of five lives is a tragedy for all the family and friends of the deceased and our condolences go to them," Mr Davies said.
"We must not lose sight that this was also a traumatic event for the police officers involved, and the members of the other emergency services who attended this terrible accident."
Post mortem examinations on those who died are expected to be concluded on Tuesday.
Rush hour traffic
The motorway was closed - in both directions - until lunchtime as investigators examined the crash scene on the eastbound carriageway between junctions 25 and 24.
Monday morning rush hour traffic tailed back for up to seven miles with all main roads across south east Wales heavily congested.
The police watchdog continues to appeal for information from anyone who saw a red Ford Mondeo travelling the wrong direction on the eastbound carriageway of the M4 near the Christchurch Road motorway bridge at around 0315 BST.
Witnesses are asked to call free phone 0800 096 9076 or e-mail firstname.lastname@example.org.
Meanwhile, in the publication of a report unrelated to this incident, the IPCC has warned that some police officers are taking unnecessary risks in high-speed chases.
The IPCC said there were no consistent rules for criminal pursuits and called for compulsory guidelines.
The Association of Chief Police Officers responded by announcing a review of its existing guidelines, which are currently advisory.