A woman and two children remain critically injured in hospital after an M5 crash that killed four people.
A lorry crashed through the central reservation at about 14:30 BST on Saturday and hit at least two vehicles heading northwards, police said.
Highways England said it expected the northbound carriageway between junctions 16 and 14, just north of Bristol, to remain shut on Sunday.
The southbound carriageway reopened shortly before 06:00.
No details of the four people killed in the crash, which happened between junctions 15 and 14, have yet been released by police.
The injured woman and children were taken to hospitals in Bristol after the crash, where they were described as being in life-threatening conditions.
The driver of the lorry was taken to hospital to be checked over as a precaution.
Supt Simon Ellis, of Avon and Somerset Police, previously said the rescue and recovery operation was “painstaking work”.
He said officers’ priorities were to notify the victims’ next of kin and thanked members of the public who “courageously went to the aid of those involved” in the crash.
Motorists were stuck for hours on the motorway following the crash.
Cardiologist Dr Amer Hamed, who was in a car travelling northbound, seconds behind the vehicles caught up in the collision, said: “There was a lorry involved and at least two other cars. One was absolutely destroyed and another had flipped over.”
Dr Hamed said that he and a GP, who was also in a car at the scene, treated an injured woman.
He said motorists who had been stuck on the carriageway for several hours were “very helpful” and had offered food and water to other people who were stuck.
Jasper Fox was travelling southbound with two friends and said they were one of the first on the scene after the collision and did what they could to help.
He said: “The crash was utterly horrific – it is not anything I’d wish anyone to see.
“We’ve been quoted as heroes but it is just human nature.”