Emergency services are dealing with a "serious" traffic accident near Carmarthen.
Dyfed Powys Police was called to the incident along the busy A40 between Llysonnen Road, Carmarthen and St Clears, at around 20:50 BST.
Mid and West Wales Fire and Rescue service and Welsh Ambulance have both sent "several resources".
Motorists are facing long delays and tailbacks with the main link road closed in both directions.
The A40 between Carmarthen and St Clears is currently closed east and west bound while Dyfed Powys Police deal with a serious RTC.— HeddluDPPolice (@DyfedPowys) October 27, 2018