The A487 is currently closed due to a collision in Talybont.
Police are asking motorists to avoid the area and find an alternative route.
In a post to social media, Dyfed-Powys Police said: “The road is currently closed due to a collision.
“Please avoid the area and find alternative routes for your journey.”
Lloyds Coaches said the collision has led to changes to its service.
“We will be unable to serve Dole, Talybont or Tre Taliesin until further notice.
“Please bear with us.”
Traffic Wales confirmed that the A487 in Talybont is closed in both directions.