Two people have died after being hit by a train between Bridgend and Port Talbot in South Wales.
The railway workers were struck by a Great Western Railway service from Swansea to Cardiff.
British Transport Police have confirmed two people were killed in the tragedy, which happened shortly before 10am.
An air ambulance was sent to the scene, but paramedics were unable to save the two.
Passengers on board the train have been told they will not be moving for at least two hours, Wales Online reports.
One person has been treated for shock.
Superintendent Andy Morgan said: “We are making a number of urgent enquiries to understand exactly what happened in the moments leading to this fatal collision.
“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.”
Unconfirmed reports claim signal workers were unaware workers were on the line.
One railway worker said: "The driver immediately called in the accident saying he had struck the three workers and ambulances were called.
"A signal worker didn't know that they were there. It could be that they hadn't notified the right people."
The Rail Accident Investigation Branch has been notified.
National Rail initially said three people had been struck.
It later posted a further comment stating: "A serious incident has occurred on the railway this morning, with two members of railway staff struck by a train."
A spokeswoman said: “The incident is still ongoing. The line is closed at the moment.”
A statement from the Welsh Ambulance Service said: “We were called on Wednesday 3 July at approximately 09:58 to reports of a collision between a train and two people in the Port Talbot area.
"We responded with two rapid response vehicles, two ambulances, two vehicles from the Hazardous Area Response Team and were supported by a vehicle of the Wales Air Ambulance.”
A passenger on board the train - which had left Swansea at 9.29am - said the train came to an abrupt stop moments after leaving Port Talbot Parkway.
He said there was a lot of shock among passengers.
The stunned passenger said: “We weren’t sure what was happening, but a train manager came through the train and said the railway workers had been hit by the train.
"We are still on the train and have been told that we are understandably going to be here for some time."
“We can see a large number of emergency service vehicles at the scene.”
Labour MP Stephen Kinnock, who represents Aberavon, posted on Twitter: "I’m very concerned to see reports of the tragic accident on the rail line between Bridgend and Port Talbot.
"I understand that there may have been two fatalities. This is awful news, and my thoughts are with the families of all concerned."
A Great Western spokesman said: “Emergency services are dealing with an incident between Port Talbot and Pyle.
“Commuters should be aware that services are disrupted while they are emergency services are on site and are dealing with the incident.”
