The derailment and subsequent fire of a freight train in Llangennech is not thought to have been caused by criminal activity, British Transport Police (BTP) have said.
The force moved onto the site on Friday alongside Network Rail and Natural Resources Wales to investigate the incident which saw three carriages of a freight train carrying a large amount of diesel go up in a ball of flames in the village, near Llanelli, just before 11.20pm on Wednesday.
Detective chief inspector Paul Langley from British Transport Police said their initial investigation of the site was over and the scene would now be passed on to the Office of Rail and Road. He thanked his officers and other emergency workers for making the area safe and added: "Our initial findings are that the derailment is not believed to have been caused by criminal activity.
"We are therefore handing primacy of the scene to the Office of Rail and Road so that it can carry out its own specialist investigation.
"I would like to once again thank our officers for their efforts during this challenging incident and I am grateful to all of our partners for their help and support in ensuring the safety of the local community."
The blaze could be seen from miles around and hundreds of people in the area were evacuated from their homes. Two workers were on the train but were not injured and raised the alarm.
An evacuation zone was put in place and police contacted residents and asked them to go to Bryn School and Llangennech Community Centre. They were allowed back into their homes at around 5.30am on Thursday.
On Friday morning Mid and West Wales Fire and Rescue Service issued a statement saying the blaze had been extinguished.
