Dozens of firefighters from Norfolk, Cambridgeshire and Lincolnshire tackled a blaze at a supermarket in King's Lynn.
Crews were called at 5.50pm on Saturday to a fire on the A149 side of the Sainsbury's supermarket at the Hardwick Industrial Estate.
UPDATE: Sainsbury's in King's Lynn closed until further notice after fire
A passer-by raised the alarm when they saw smoke and flames coming from one end of the building.
Staff quickly evacuated the building and have been praised by the fire officer in charge of the operation for their swift actions.
A spokesperson for Sainsbury's has confirmed that the store is closed until further notice.
Fire crews from Lynn, Downham Market, Sandringham, Wisbech, Long Sutton, Terrington, Hunstanton and Massingham spent about three hours at the store.
The aerial ladder platform was also called and firefighters wore breathing apparatus and a thermal imaging camera to check for hotspots.
In a post on social media, the fire service urged people to stay away from the Hardwick area of Lynn.
The ambulance service was called to the scene but was stood down once fire crews ascertained that no one had been injured and no medical care was needed.
Video footage captured at the scene by local company Drone People captured the firefighting operation.
Business owner Graham Cooke had popped into Sainsbury's after filming the Hunstanton Rocks Battle of the Bands, so he already had his drone equipment in his car.
Group manager David Copeland, who was in charge of the fire operation, said: "Behind the wood cladding is a timber frame with insulation. The fire had spread behind the timber cladding and had ignited the insulation.
"The crews had to remove the timber cladding to get to the seat of the fire to make sure it had not spread even further.
"It was very arduous but our crews did an exceptional job."
He praised the Sainsbury's staff.
"They responded exceptionally well and promptly in evacuating the building. By the time our crews had arrived the store was completely evacuated which then for us means we did not have to commit crews into the building, putting lives at risk."
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