Firefighters were still on the scene this morning to damp down and extinguish any hotspots following the blaze in a warehouse that had been damaged by a previous fire.
At the height of the fire, more than 50 firefighters were on the scene with eight fire engines, an aerial rescue pump and a number of supporting appliances.
There had been initial reports that someone may have been inside but everyone was accounted for and no one was hurt.
Avon Fire & Rescue Service said their control room received more than 30 calls to the incident as thick black smoke could be seen across a wide area. Local people were asked to avoid the area and close all doors and windows as a precaution due to the smoke.
Around 26 people were evacuated from their homes in the local area for a time due to the smoke.
This afternoon a spokesman for the fire service said: “Fire investigation officers have been working with crime scene investigators from Avon & Somerset Constabulary to determine the cause of the fire. It’s thought it was started deliberately.”
Goldmark Scaffolding’s unit backs on to the one that was destroyed in the blaze and the searing heat penetrated the wall, leaving scorch marks. Business owner Mark Collinson said the unit where the blaze occurred was not occupied but had become a fly-tippers’ dumping ground following a blaze about two years ago.