The main road through Llanwrtyd Wells will be closed for five days after a car crashed into a shop.
The A483 has been closed for safety reasons amid concerns that the Premier Stores shop could collapse.
Powys County Council said there is a fully signed diversion via Brecon and Llandovery.
The road closure is in place following a "serious" collision in the early hours of Friday morning (January 24).
Two people were taken to hospital in Abergavenny after a Renault Clio crashed into the convenience store on Irfon Terrace.
Emergency services responded to reports of a collision at around 12.30am.
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