The Philadelphia Fire Department and PGW were called to the 2500 block of South Mole Street around 11 a.m.
PGW said workers found a leak in a 4-inch gas main.
People in four homes were ordered to evacuated, while people in as many as four other homes chose to voluntarily evacuate.
PECO has turned off power to the block while repairs were made.
No injuries have been reported.