The blaze broke out before 12:17 p.m. Wednesday at 1301 Federal Street.
Firefighters arrived to find heavy fire coming from the third floor.
It took crews about 30 minutes to get the situation under control.
Medics took one man to an area hospital for treatment.
Two women and two children from the home at 1305 Federal Street had to be evacuated.
The Red Cross is assisting them.
Investigators are working to determine what sparked the blaze.