Fire broke out in an 18th century building in Nutley High Street just before 10am on Wednesday morning, August 7.
Flames penetrated the roof space and the building was gutted.
Crews from Uckfield, Crowborough and Forest Row attended with breathing apparatus, two jets and a command vehicle.
One firefighter was admitted to hospital but discharged within an hour.
A police cordon was thrown around the scene and the main A22 was closed from the Batts Bridge Roundabout at Maresfield to the junction with the A22 and the Crowborough road.
Road restrictions caused traffic gridlock as they coincided with resurfacing work and diversions on the A272 at Piltdown.
The building, called The Old Bakery, was examined by Wealden’s building control officer and a decision is due be taken as to whether it can be restored or needs to be demolished.
Tim Neill from the village told the Express he heard a ‘terrific bang, like an explosion,’ a report confirmed by resident Steve Ayres.
Steve said: “We went for a walk on the Forest at about 7.45am and all was quiet then.
“When we came back after about two hours I saw smoke billowing out of the house and then heard the explosion. I went to fetch my camera.”
Shocked villagers lined the street.
Paul and Rosemary de Souza used to live in The Old Bakery and arrived in Nutley yesterday to house-sit for friends.
The couple, who live part of the time in Sutton, Surrey and the rest in Franschhoek (correct spelling,) South Africa, said: “The first we knew was when we heard the bang and then smelt a chemical smell.
“There was a terrific boom. We were told that a medical oxygen cylinder had exploded on the site.
“When we first heard the sound we thought it came from the Crowborough Shooting Club grounds but realised it was more serious than that.
“It’s terrible to see what’s happened to the cottage - we had wonderful times there.”