The transport secretary has said it could be "weeks" before the causes of the M5 tragedy are known - as it emerged the seventh victim of the crash was a father-of-four.
Kye Thomas, 38, from Gunnislake, Cornwall, leaves two sons and two daughters.
Mr Thomas, originally from Plymstock, Devon, served in the Army with the King's Royal Hussars before becoming a lorry driver for Samworth Brothers, according to his Facebook page.
His widow Rebecca confirmed he was killed in the pile-up but did not want to make any further comment. Mr Thomas' friend Andy Keith paid tribute to him on Facebook.
He wrote: "RIP to a great friend Kye. What a shock, I've just found out and our hearts go out to Rebecca and their children, another great person gone going to miss you."
The stretch of the road, near Taunton in Somerset, has now reopened following Friday evening's 37-vehicle smash, in which seven people died and 51 were injured.
Police investigating the accident are focusing on a fireworks event held near the scene at Taunton Rugby Club.
But Transport Secretary Justine Greening warned against speculation surrounding the accident.
"It was humbling and inspiring to see how selflessly so many people were willing to offer their support to others who needed it," she told the House of Commons.
"It would be a mistake at this very early stage to speculate about the causes of the collision.
"While Avon and Somerset Police have indicated that the presence of smoke on the carriageway is a significant line of inquiry, Assistant Chief Constable (Anthony) Bangham has indicated to me that it's far too early to jump to conclusions on the causal factors of this incident and our first priority now must be to ensure that the police are able to conduct a comprehensive and thorough investigation of the crash.
"He told me that given the large number of vehicles involved, the need to carefully look at those vehicles recovered and, of course, to talk to many of the witnesses, it may be some weeks before the until the investigation can conclude on any... causes of this incident."
Investigators say the suggestion that smoke from the display had drifted across the road and caused the pile-up was now their "main line of inquiry".
Mr Thomas was one of two drivers working for Leicestershire-based food producer Samworth Brothers, owners of Cornish pasty makers Ginsters, who died in the accident.
Lorry driver Terry Brice from Bristol was named as the other one of those two drivers. A third driver from the company was injured in the accident.
A Twitter post, believed to be made by Mr Brice's teenage daughter Jessica, said: "rest in peace daddy, i love you so much, you will never be forgotten, not a day will go by where i won't hope you'll walk through that door."
Samworth Brothers, based in Melton Mowbray, said it was "very shocked and saddened" by the tragedy.
Company director Mark Samworth said: "The thoughts of everyone at Samworth Brothers are with the families and friends of all these individuals and others involved in this terrible incident."
Meanwhile, consultant in emergency medicine at Taunton's Musgrove Park Hospital, Dr Clifford Mann, described what staff were faced with in the aftermath of the crash.
"We normally have one resuscitation going on at any one time, (but) on Friday night there was at one point six resuscitations going on simultaneously," he said.
"There was a whole gamut of injuries really. I mean, any injury you might expect from a road traffic accident, we had an example of."
The Reverend Andrew Willie told a congregation at St Mark's Church, where the couple attended, that they had died.
He said Mr Adams, who was a church reader and former warden, and his wife, who was involved in parish activities, "will be sorely missed".
Neighbour and close friend Doreen Martin, 88, said the pair were in their 70s and had a large family of children and grandchildren.
"It's such a shock. They were a lovely couple," she said.
Meanwhile, it is reported that the crash has left a young woman in a coma and her wheelchair-bound father and sister dead.
Emma Barton, believed to be 19, was said to have been travelling in a car with her boyfriend Christopher Burbull, father Michael and sister Maggie, when they were caught up in the chaos.
Mr Burbull, of Slough, Berks, was also admitted to hospital following the crash, it was said.
Another casualty of the accident was named as Malcolm Beacham, from Woolavington in Somerset.
Online tributes on Monday night appeared in memory of Mr Beacham, who is said to be the event co-ordinator of a re-enactment group.
One comment, left on the Living History website by a user named Martin, said: "For those that had the privilege of knowing him Malcolm was a fantastic guy, a true stalwart of the re-enactment community from The Company Of Chivalry, he was involved in the accident on the M5 on Friday, you will be sorely missed m8."
Matt and Michelle Craker spoke to Sky News about their miraculous escape along with son Freddie, after their van was caught in the centre of the pile-up.
"(It was) almost as if someone had put their hands over your eyes... like you'd been blindfolded."
Mr Craker added: "We were just so lucky. Within a couple of minutes of us having got out of the van, there were flames in the van.
"If we had been knocked out or anything like that.. the fire was just so close behind us. It was unbelievable."
Police inquiries into the firework theory started after witnesses reported "significant smoke" across the carriageway that was "impossible to drive through".
Asst Ch Con Anthony Bangham said: "Our main line of inquiry has now moved towards the event that was on the side of the carriageway and we do believe that while there was fog and it was difficult conditions in the area, that actually from witness evidence there was very significant smoke across the carriageway.
"That in effect caused a bank similar to a fog bank, which was very distracting and very difficult to drive through.
Witnesses at the Taunton Rugby Club fireworks display were being interviewed, he said, adding that accountability was "clearly something we will look at".
He went on: "We believe from the witnesses and from what we're being told that it was smoke and not fog.
"The vehicles and people who were entering into the smoke bank have just described it as being impossible to drive through and that of course causing them to brake."
Taunton Deane Borough Council confirmed that organisers of the fireworks display at Taunton Rugby Club did not require a licence for the event.
And transport minister Mike Penning, said it was possible the thick, black smoke reported by some witnesses may have been produced by the initial collisions rather than conditions before the crash.
"Once these lorries caught fire, diesel produces a very black acrid smoke, the tyres were alight, the plastics were alight," he said.
"That mixing with mist or fog would create something that people might have thought was there before but was not there before but was part of the accident."
Emergency workers described the crash as "the worst road traffic collision anyone can remember".
The motorway was closed in both directions between junctions 24 and 25 following the incident, which took place at about 8.25pm in wet and foggy conditions on the northbound carriageway.
Of the casualties, 25 were taken to Yeovil District Hospital and 17 of the more seriously injured to Musgrove Park Hospital in Taunton. Nine others were taken to a temporary holding unit set up by the ambulance service.
Musgrove Park Hospital said 11 people were still being treated there.
Formal identification of the victims is expected to take place in the coming days, police said.