A fire which caused the evacuation of 100 homes and some businesses is thought to have started accidentally.
Firefighters were called to a commercial garage blaze in Derby at 18:56 GMT on Saturday.
The fire service was prompted to evacuate due to "the presence of commercial cylinders" and residents spent the night at a refuge centre.
They went home on Sunday except a "couple of families" whose homes have "significant structural damage".
Derbyshire Fire and Rescue Service said following a joint police and fire investigation, the "most probable cause of the fire was accidental".
Twyford Auto, where the fire started, also had "significant damage", the fire service added.
Station manager Adam Bleakman said the "couple of families" who were unable to return home on Sunday night were at a hotel, and Derby City Council was working with them to find new accommodation.
Mr Bleakman added that it was a "challenging" incident and that evacuating the homes was "not a decision taken lightly".
He added that no-one was injured in the blaze.
Yashpal Manan, who runs an electrical business behind the garage and owns six flats next to it, said "the fire spread so fast".
"One of my warehouses caught fire. We had to demolish one of the buildings because it wasn't safe," he said.
Mr Manan added that the 14 or 15 tenants were living in temporary accommodation and he was hoping to move three families back in by Tuesday.
However, he said the rest "is difficult because there is a lot of work to be done".
He added that "sorting the flats out is a priority now".