South Wales Police say 12 vehicles have been involved in a crash on the A465 between Glynneath and Hiwaun this evening.
One person has been taken to hospital with injuries not believed to be serious.
The road remains closed as emergency services work to clear the area.
More top news
Missed Tuesday's Wales at Six? You can catch up here.
Police say the road is currently closed in both directions between Baverstocks and Hirwaun and is expected to remain closed for some time.
All 555 of Thomas Cook’s travel agencies in the UK were acquired on short-term leases by Hays Travel.