The break happened around 8:45 a.m. on Route 4 (West Newport Pike) in the area of Adelphia Avenue and West Newport Pike in Silview.
Construction crews were working to install new water mains when they struck the gas main.
Delmarva Power Company crews are on the scene. A Delmarva spokesperson says they will have to close off the 1-inch gas service line, which leads to one home, for repairs. Only that one customer was effected and serviced should be restored to that home by 11:00 a.m.
An auto repair shop and two other small businesses have been evacuated.
At last check, only one lane of Route 4 eastbound remained closed.