Two railway workers have died after being struck by a train near Port Talbot in South Wales, police said.
The “serious incident” involved two people working on tracks at Margam, Network Rail said.
Welsh Ambulance Service said it was called just before 10am to reports of a collision between a train and two people
Superintendent Andy Morgan, of the British Transport Police, said: “We are making a number of urgent enquiries to understand exactly what happened in the moments leading to this fatal collision.”
He added: “Very sadly two people have died and my officers are now working to identify them and ensure that their families are supported at this incredibly difficult time.”
The Rail Accident Investigation Branch said two inspectors were en route to the scene.
Transport Secretary Chris Grayling said he would ensure “lessons are learned” following the incident.
Alternative arrangements are being made for passengers affected by delays on the busy route, which will be blocked in both directions until further notice.
Bill Kelly, Network Rail’s route managing director for Wales, said: “We are shocked and distressed to confirm that two members of our team lost their lives today in an accident involving a train.
“We do not know the details behind this dreadful accident and we are fully cooperating with the British Transport Police and Rail Accident Investigation Branch.
“Our thoughts are with the families of our colleagues and our members of staff who will be affected.”