Crews responded to the fire in the 9000 block of Continental Place in Landover at approximately 3:30 a.m., according to a department press release.
They found heavy fire to both floors of the two-story middle unit upon arrival.
A volunteer firefighter from the Kentland station fell through a hole in the first floor down into the basement. He was able to pull himself out and was soon evaluated by paramedics on the scene.
He was transported to the burn unit at Washington Hospital Center with a "significant" second-degree burn to his back.
He is listed in good condition but will remain hospitalized for additional treatment.
There were no other injuries reported and the townhouse was unoccupied as it was under renovation.
The cause of the fire is under investigation and damages are estimated at $100,000.
