Drivers are being warned to avoid the A4159 Bow Street to Lovesgrove road following a crash at the site.
Dyfed-Powys police issued the warning on social media.
A post on Facebook says: “The road is currently closed due to a collision.
“The junction off the A487 to Penrhyncoch crossroads are also closed.
“Please avoid the area and find alternative routes for your journey.”