The Arlington County Fire Department responded to a commercial fire alarm at about 7 p.m. Thursday at 14th Street North and Courthouse Road.
The fire was in a back room of a dry cleaning business, one of three retail establishments in the county-owned Thomas Building.
Responders knocked the fire down "pretty quickly," Capt. Gregg Karl told Patch. Karl was unaware of any injuries.
At about 7:30 p.m., firefighters remained on scene checking to make sure the fire didn't spread to adjacent businesses or nearby buildings.
"It sounds like it was pretty much contained to a back room," Karl said.
Damage estimates were not immediately available.
Arlington County bought the Thomas Building, at 2020 14th St. N., in November to convert to county office space and a year-round homeless service center.
The previous owner agreed to sell under threat of condemnation.
The three retail tenants, including Ragtime, are expected to remain in the building.