A 51-year-old lorry driver has been arrested following a crash in which four people were killed.
The German national was arrested on suspicion of dangerous driving after the crash at junction 11a on the M6, at Great Saredon in Staffordshire.
The four victims, two Birmingham men and a couple from Stoke-on-Trent, were in two cars involved in the pile-up.
Less than an hour earlier on Sunday evening a woman was killed when a van overturned on the M6 near Keele.
In the multiple pile-up, which took place about 1940 BST, a number of people had to be cut free from their vehicles with two taken to hospital suffering from suspected spinal injuries.
The vehicles involved were a Ford Mondeo, a Renault Clio and three lorries.
Two men, aged 52 and 30 and from Birmingham, travelling inside the Mondeo and a man and woman from Stoke-on-Trent inside the Clio were killed.
A lorry driver was cut free from his vehicle and received treatment for whiplash.
A Highways Agency spokesman said: "Extensive damage was caused to the vehicles involved. It's quite a phenomenal tragedy.
"From our viewpoint, despite being at the scene within eight minutes, sadly it was to no avail for those four people."
He added: "We don't know why the collisions happened. We would ask anyone who knows anything to come forward."
In the first incident the woman, a passenger in the van, died when the van overturned on the southbound carriageway.
The accident took place shortly after 1900 BST between junction 16 and the Keele services.
She was pronounced dead at the scene and all three carriageways were closed for several hours.
Many motorists stuck on the southbound carriageway for up to five hours abandoned their vehicles and walked to the nearby motorway services.