Four people, including three men travelling in the same car, have been killed in motorway crashes as families hit the roads for half term breaks.
The two fatal crashes happened within an hour of each other this morning and caused traffic to come to a virtual standstill.
A 40 vehicle pile-up in thick fog on the M4 in Oxfordshire left one man dead, another person fighting for life and injured 40 more.
Witnesses described scenes of “carnage” as cars were left crushed and debris strewn across the road following the crash, which happened just before 8am.
An hour earlier at 6.46am a double-decker coach collided with a stationary car on the hard shoulder on the M1 near Flitwick, killing three men in the Audi A3 and hospitalising a fourth.
Two of the men who died on the M1 were from Buckinghamshire and one from London.
Police said the M40 crash, which happened between junctions 9 and 10, was an “extraordinary” and “horrible” accident, and it is a “serious blessing” more people were not injured.
A red car at the front of the pile-up was almost entirely crushed, while other vehicles stood scattered with their front bumpers damaged and squashed.
Zara Smith, 31, described the crash as “carnage” and said she saw a “sea of metal” in the road ahead.
She was travelling from Croydon in south London to Stockport with her fiance for a family holiday when they saw dozens of ambulances and police cars whistle past as traffic came to a standstill.
She said: “It was really thick fog and difficult to see that far in front so no one really knew what had happened. We were there for an hour and a half and then police diverted us down a slip road.
“It was at that point that the fog started to rise and a mile ahead you saw this carnage.
“There was one large lorry which had jackknifed and was across three lanes of the motorway, and all these cars ahead of it. It looked like a sea of metal.
“There was a lot of debris. We hadn’t been aware of how close we actually came to it because of the thick fog.
“It was really dense fog. For about half an hour driving before the accident we were going in and out of patches of fog. By the time we stopped we could only see one or two cars in front.
“The crash was shocking. We had stopped for coffee and petrol on the way and you think ’God, if we hadn’t have stopped we could have been in it’, but you can’t think that way.”
The stretch of motorway was closed northbound, causing gridlock.
A man was pronounced dead at the scene. His family have been informed.
Another person is fighting for their life, six people were seriously hurt and up to 45 more suffered minor injuries in the collision.
Chief Inspector Henry Parsons, head of Thames Valley Police’s roads police team, said the crash was an “extraordinary” and unusual accident.
Speaking in front of debris scattered on the road, he said it is a “serious blessing” that more people were not killed in the pile-up.
Officers are investigating what caused the crash, and believe thick fog was a contributory factor.
Mr Parsons said: “It is very extraordinary. We haven’t been hit by an accident this severe for many years in Thames Valley.
“It does very much touch you personally. It is a horrible scene and ultimately one person has lost their life and several are seriously injured as a result. It is awful, whatever way you dress it up.”
Commenting on what caused the crash, Mr Parsons said: “It would be too early to say with any certainty, but clearly the fog will play a major part in our investigation.”
Meanwhile Bedfordshire Police said the man injured on the M1 is from Buckinghamshire and remains in the John Radcliffe Hospital in Oxford with serious injuries.
The coach driver was arrested in connection with the incident and taken to Luton Police Station where he is being interviewed.