The break on the 16-inch main happened shortly after 1:00 p.m. while a road crew worked along N. Pemberton Road, near Brandywine Road.
Hazmat and PSE&G crews responded to the scene and the roadway has been shutdown in the area.
PSE&G crews have reportedly turned off the leaking gas line and are now working on repair.
There are no injuries reported. Also, there is no word of any evacuations at this time.