Fire officials and medics were called around 7:00 a.m. to the 1800 block of N 76th Street.
Medics evaluated one adult and one juvenile at the scene.
After checking several houses on the block, fire officials determined three homes had high levels of CO. Crews then ventilated the properties.
PGW was also called to the scene.
So far there is no word on the source of the carbon monoxide.