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.
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Rain clipping the far north through the evening but elsewhere staying dry with some sunny spells.
Public Health Wales figures show 25 more cases of the virus have also been confirmed.
Photos taken on Saturday morning show Roald Dahl Plass strewn with empty beer bottles and discarded canisters of laughing gas.