Crews were called to the 700 block of Flora Avenue at around 5 a.m. to extinguish a blaze near Arlington Street.
The firefighter who was taken to hospital is in stable condition and is said to have twisted his knee, according to those on scene.
Traffic in the area was snarled until around 6 a.m., when the blaze was finally put out.
No word yet on what caused the fire. Damage is estimated at $200,000.