Authorities reported the blaze around 5 p.m. in the 22100 block of James Alan Circle. The fire ripped through the roof of the structure and destroyed about four units.
Firefighters said the four units shared an attic in the 47-year-old wood frame and stucco building.
One firefighter suffered a cut to their hand, while the other ended up with a dislocated shoulder. One civilian was checked over for smoke exposure.
The blaze was knocked down by 6:15 p.m., with about 122 firefighters working to put it out.
The American Red Cross offered assistance to four displaced families.
Investigators considered the fire accidental and believe it started with the installation of propane or barbecue equipment on a condo's patio.