The fire erupted around 3:00 p.m. in the 1000 block of Willow Street.
Images from Chopper 6 HD over the scene showed flames shooting through the roofs from two non-adjoining units.
Authorities say two of the homes were vacant.
By 5:00 p.m. firefighters had gotten a handle on the blaze, though smoke could still be seen pouring from the buildings.
Al Johnson, who owns some of the homes on that street, saw the fire first-hand.
"When I first got here I could see flames jumping out there and smoke billowing out from the chimneys on the roof. It was chaotic," Johnson said.
A firefighter was taken to the hospital for a minor injury. There were no reports of injuries to the residents.
The Red Cross was helping 21 people displaced by the blaze.