An investigation into the blaze at a building on Rectory Road, Retford yesterday morning has found it was started deliberately.
Fire crews from stations in Worksop, Harworth and Retford were called to the blaze at 4.47am on Thursday, May 27.
Nottinghamshire Police is now investigating.
A Nottinghamshire Fire and Rescue spokesman said: “A fire investigation has concluded the cause was deliberate ignition due to a naked flame coming into contact with combustible materials.
"The police have been informed.”