UPDATE: Sky News is reporting that the coach involved in a crash on the M5 had broken down on the motorway when it was hit by a lorry.
UPDATE: Police this afternoon arrested the 49-year-old coach driver on suspicion of causing death by dangerous driving. He has been released on bail pending further enquiries.
One person was killed and 40 others injured when a coach and lorry crashed in fog on a motorway today.
Two people were seriously hurt in the accident near Frankley Services on the M5 in the West Midlands.
Forty people were treated at the scene, on the southbound carriageway between junctions three and four.
Police said the death and one serious injury were from the coach, and the driver of the lorry was also in a serious condition. No children were involved.
West Midlands Ambulance Service said a large number of resources had been sent to the scene on the southbound carriageway of the M5 between junctions three and four.
A spokesman for the ambulance service said several ambulances, rapid response vehicles and a hazardous area response team had been deployed to the incident along with doctors and ambulance officers.
The spokesman said a number of patients were currently being conveyed to various hospitals across the area.
"Whilst the majority of patients appear to be walking wounded there are a small number with potentially serious injuries," the spokesman added.
West Midlands Police said no children had been involved in the accident and confirmed that the driver of the lorry was among those seriously injured.
The affected stretch of the M5 is likely to remain closed in both directions for a considerable time and motorists are being advised to find alternative routes.
Eye witness Paul Guppy told BBC News that there were fog patches on the motorway at the time of the crash.
He was driving on the opposite carriageway at about 6.40am.
"There were fog patches, because I was driving through it with my fog lights on. That area is renowned for having fog, there's a lot of low-lying land.
"It was quite horrendous at the time, and then it cleared. Whether the fog was a contributory thing, I don't know."
The coach seemed to have been hit from the rear, on its offside, and was leaning, virtually intact, against a crash barrier, he said.
A number of passengers on the coach had non life threatening injuries and were receiving medical attention.
Police were called at approximately 6.24am via a 999 call to reports of a serious road traffic accident.
West Midlands Ambulance Service said later that 40 people had been assessed and treated at the scene, of whom 27 had been taken to various hospitals around the region.
Ambulance crews took injured people to Queen Elizabeth, City and Sandwell hospitals in Birmingham, and Alexandra Hospital, Redditch.
West Midlands Ambulance Service assistant chief ambulance officer Steve Wheaton told Sky News: "It was a very foggy stretch of road this morning. Police are investigating the exact cause, but the weather has not been helpful."
The coach involved in the crash carried a logo of the company Stagecoach, but a spokesman for the firm said it had been sold to a dealer 18 months ago.
The spokesman did not know who it was sold to.