Both trains were travelling in the same direction and one train struck the side of the other, causing it to derail.
The front carriages remained upright, whilst the back ones tipped on their side.
92 passengers are said to have been on board, with 30 attending a casualty centre at a nearby church. Majority of those were walking wounded, however, 13 were taken to hospital by ambulance and treated for minor injuries.
However, sadly, the driver of the train was more seriously injured, with the British Transport Police saying they are thought to be ‘life changing’ rather than life threatening. He is a stable condition in hospital and his family has been informed.
The BTP has said that at this early stage, there are “nothing to suggest” that one train struck and object and there was no significant delay between the trains colliding and derailing, which has been reported in the media this morning.
A spokesperson said “Thirteen people were taken to hospital by ambulance where they have received treatment for minor injuries. One remains there. ”
“Unfortunately, the driver of the train was more seriously injured and his injuries are believed to be life-changing. He also remains in hospital in a stable condition this morning, and his family have been informed.”
“We have now moved out of the rescue phase of the operation and into the investigation which will involve the trains remaining in situ for some time. The investigation remains at an early stage but a senior detective has been appointed to lead the enquiries as we work to establish the full circumstances of how this incident came to happen. ”
Detective Chief Inspector Paul Langley said: “This will no doubt have been an incredibly frightening experience for all those involved and our thoughts are with them and their families today.
“Specialist officers and detectives remain on scene in Salisbury and we are working closely alongside the Rail Accident Investigation Branch (RAIB) and the Office of Rail and Road to establish exactly how these two trains came to collide.
“We are keeping an open mind but at this early stage there has been nothing to suggest the train struck an object or that there was any significant delay between the trains colliding and then one derailing.
“This has been a large scale, multi-agency operation and I would like to pay particular to thanks to our emergency service colleagues for their efforts in safely evacuating passengers, and to the many members of the local community who reached out with offers of help.”