Update at 5.30pm on 27 August - Superintendent Andy Morgan said: “We have continued to respond to the major incident on the railway line near Lllangennech throughout this afternoon, alongside many of our partners.
"Officers are conducting initial enquiries and have now been able to take a look at the train from a safe distance. We await further guidance on when it will be safe for us to fully access the scene. Once it’s safe to do so, our colleagues at Natural Resources Wales will also be working to fully assess the environmental impact and advise Network Rail when the clean-up of the site can begin.
Superintendent Andy Morgan said: “Overnight, officers from British Transport Police, Dyfed-Powys Police, the Mid and West Wales Fire and Rescue Service, ambulance service and Carmarthenshire County Council dealt with a major incident on the railway line near Llangennech.
"We have launched an investigation and will be assisting the Office of Rail and Road and the Rail Accident Investigation Branch to establish the exact circumstances behind the incident.
"What we know is a freight train, carrying large amounts of diesel oil, caught fire and a number of its wagons also derailed. Thankfully, despite the clear danger, no injuries have been reported. The two members of railway staff operating the train were able raise the alarm and uncouple the locomotive and move it to a safe space.
"The fire was significant due to the quantity of fuel it was carrying and presented a possible danger to the wider community.
"As a precaution, roads were shut, and Dyfed-Powys Police evacuated a large number of homes within a radius of the fire.
"I believe around 300 people were affected and I’d like to thank everyone for their understanding and quick action in what must have been a frightening time.
"At this time, the cause of the fire is unknown and, while the fire continues, there is still a substantial risk within its immediate vicinity, so our advice remains for people to avoid the area.
"Our officers are conducting initial enquiries and are in the process of collecting key witness statements and CCTV. Once the fire is extinguished, and the scene is safe to assess and investigate, they’ll be assisting the ORR and RAIB further at the scene.
"This was and remains a very challenging incident. I’d like to thank all of our partners for their ongoing support and work to ensure the safety of the surrounding community.”