The fire was reported at 6:20 p.m. on Linkshead Court near Millbrook Elementary School, fire Capt. Mike Van Elgort said.
Multiple calls reported two homes on fire, Van Elgort said, and immediately after arriving firefighters called for a second alarm response and 30 minutes after that a third alarm.
A gas meter had broken off one of the homes and was leaking burning gas, hastening the spread of the fire.
"By the time we had arrived it had broken free and was certainly feeding the fire," Van Elgort said.
However, firefighters have not yet determined if the gas leak initially caused the fire.
It was eventually controlled without spreading further by 7:12 p.m. But both single-story homes sustained moderate fire damage, leaving 12 residents displaced. At least four of the residents are children.
Most of the residents were not home when the fire started and no one was injured, Van Elgort said.