The firefighters were taken to Stroger Hospital where they were alert, talking and "resting well," said First Deputy Fire Commission Annette Nance-Holt.
Just after 8 p.m., Chicago firefighters responded to a fire at a three-story apartment building in the first block of South Albany Avenue. About 100 firefighters and EMS were on the scene.
The firefighters fell from the third floor to the first floor. A mayday call was issued, but all the personnel were soon accounted for, Nance-Holt said.
"It happened relatively fast," she said.
One escaped the building on their own and the other was helped out, Nance-Holt said.
The third and second floor of the building were vacant. The building had no working smoke detectors.
Nance-Holt called the fire routine, but did not immediately know why the firefighters fell through the floor.
The Office of Fire Investigation (OFI) Division is investigating.
A firefighter was injured battling a blaze in January at a construction site in the Loop.