A suspected arson attack at a derelict Victorian fertiliser factory was likened to “a disaster film” scene.
Fire crews were called to the Grade II-listed former Fisons warehouse on Paper Mill Lane, in Bramford, near Ipswich, at about 05:00 BST.
No one is thought to have been hurt, but the building, dating back to 1858, was destroyed by the blaze.
Ian Bowell, from Suffolk Fire and Rescue, said there was “no obvious natural cause” for the fire.
“I have to say quite confidently that we are treating this as arson,” he said.
About 60 firefighters from both Suffolk and Essex fire services were called to the blaze, which is thought to have started in a smaller building before spreading to the wooden main factory building.
Efforts to fully extinguish the fire are expected to go on for most of Monday and people living nearby have been told to close their windows and doors.
Samantha Pemberton, who lives opposite the scene, said she and her family were “met by a wall of fire” when they looked outside.
“There were embers bigger than the size of your hand falling,” she said.
“It was like walking onto the set of a disaster film.”
Paper Mill Lane was closed between Bramford and Claydon.
Fisons, a now defunct fertiliser company, operated at the site until 2003.
In 2014, a plan to turn the site into a £20m housing and business park was approved by councillors, but work had not begun.