The Poundstretcher store in Blackwood is being demolished following a blaze in the early hours of Wednesday morning.
South Wales Fire and Rescue Service say the cause of the fire was bins being set alight.
Fire crews were called out at around 2 o'clock this morning.
Officers say refuse bins were on fire and this had spread to the store room at the back of the shop.
Due to safety concerns the High Street was closed and the electricity supply to a number of shops was cut. Structural engineers were called out to assess the safety of the building.
More top news
A man who was being held at Parc Prison in Bridgend has died after being found in his cell by staff on Thursday.
A dry night with clear skies, but it will be followed by a really rather beautiful weekend!
Former Wales rugby captain Gareth Thomas in bid to make indecent and homophobic chanting illegal.