Both Arriva Trains Wales and Network Rail tweeted messages reporting the incident and reporting that the line had been closed some time after 6pm today, Tuesday, (Feb 27).
National Rail tweeted;
A person has been hit by a train between Carmarthen and Llanelli which is causing disruption to journeys between these stations. Services may be cancelled, delayed or revised. We anticipate disruption will continue until 21:00.
The line has now been reopened. No further information is available at this present time.