A train driver involved in a crash at the weekend suffered “life-changing injuries”, police have said.
Two trains collided on the approach to a tunnel in Salisbury, Wiltshire, at around 6.45pm on Sunday.
The driver of a South Western Railway (SWR) train, who was seriously injured, had to be rescued after being trapped in his cab.
British Transport Police (BTP) said on Monday: “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.”
BTP said the SWR train running from London to Honiton, Devon struck the side of a Great Western Railway (GWR) service from Southampton to Cardiff as they both entered Fisherton Tunnel.
This caused the SWR train to derail, tipping its rear carriages onto their side.
The crash happened at a Y-shaped rail junction, with the trains approached the tunnel in the same direction but on separate tracks.
A rail industry source told the PA news agency the trains collided at the point where the tracks converge.
Previous crashes in similar circumstances have been caused by a variety of reasons, such as signalling failures, trains passing through stop lights, and train brakes struggling due to leaf fall.
Ninety-two passengers were on the trains involved in the Salisbury incident.
It was initially believed that a carriage of one train derailed after hitting an object, with the second train crashing into it after signalling was damaged.
But this version of events is now known to be false.
BTP 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.”
Network Rail, GWR and SWR said in a joint statement: “While we’re thankful the majority of customers and colleagues have now been able to go home safely, unfortunately it has become clear that a driver sustained a more serious injury and continues to be treated in hospital.
“We know everyone in the railway family is wishing him a full and swift recovery.”
Railway engineer Gareth Dennis said the purpose of signals is to “stop one train hitting another”, and the fact that has not happened “means that there has been there has been a breakdown somewhere”.
A Downing Street spokesman said the Prime Minister’s thoughts “remain with those who were affected by the incident”, adding that the Government was investing to ensure Britain’s rail network remains “one of the safest in the world”.
BTP, the Rail Accident Investigation Branch and the Office of Rail and Road are all investigating what happened.
The trains remain at the scene, and services through Salisbury are expected to be disrupted until next week.
Transport minister Chris Heaton-Harris paid tribute to those injured in the rail crash, asking that MPs send their “best wishes to those who are injured and those who are affected in what happened there”.
He added: “There are plenty of lessons I am sure that will be learned but we are at the very early stages of the investigation and I am sure I will get the opportunity to inform the House about that later, but I think it would have been remiss of me not to have said something at this point.”