The blaze broke out around 2:45 a.m. on the 2100 block of 10th Street.
Crews arrived to find heavy flames showing on the second floor of one of the twin houses.
The fire started in the rear of the house then quickly spread to the roof area of the adjoining twin.
One fighter suffered minor burns and was checked out at the hospital.
An occupant in the neighboring house was also check for a minor injury.
The Red Cross arrived on the scene to assist the displaced residents.
So far, there is no word on what sparked the blaze.