The main A470 road has been closed near Talerddig amid reports of an accident involving at least one train.
Dyfed Powys Police said the road had closed, and it was understood that at least one air ambulance was on the scene.
There have been unconfirmed reports that two trains were involved in an incident.
Police, fire service, and ambulance personnel are on the scene, and the road has been closed to allow access to the area.