Officials say the leak started at about 12:30 on Friday morning inside a vacant home on the 5400 block of Vine Street.
When firefighters went into the twin house attached to the vacant dwelling they found high CO levels on their meters.
The four adults and three children were overcome by the fumes.
The adults were taken to Hahnemann Hospital and the children were transported to Children's Hospital of Philadelphia.
Officials say the victims have mild to moderate CO poisoning and are all in stable condition.
There's no word yet on the exact source of the fumes.