The Madison Fire Department was called to an early-morning fire at the Greenway Plaza on the city's south side.
Fire officials said they were called to 1325 Greenway Cross after a passerby saw flames and smoke showing.
Firefighters arrived to find smoke showing from the exterior of the building. Crews entered through a front entrance that leads to a common hallway. They said they found smoke, flames and smoldering embers on the floor.
Crews knocked the fire out at about 6:45 a.m. They stayed at the scene to watch for any remaining hotspots.
Damages are still being calculated but are expected to exceed $500,000, officials said.
Businesses at Greenway Plaza include Greenway Crossing Montessori, Panaderia & Taqueria Marimar, El Palacio, a clothing store, and Madineh Academy of Madison.
The cause of the fire remains under investigation.