A gas company spokesperson said the gas leak was caused by third-party excavation damage.
It was expected to be secured within the hour.
Raleigh Police said traffic from I-440 will be affected. Drivers are encouraged to seek alternate routes.
Major crash closes busy stretch of Capital Boulevard
A four-vehicle crash closed all lanes along southbound Capital Boulevard/US 1 near Durham Road/NC 98, while northbound Capital Boulevard/US 1 has been reduced to one lane.
The crash caused major delays, but the lanes reopened about 3:30 p.m.
No serious injuries were reported.