The leak is off Wade Avenue at Saint Mary's Street. It was capped about 4:30 p.m. and repairs are ongoing.
Wade Avenue was closed between Glenwood Avenue and Woodburn Road and St. Mary's Street between Wirewood and Williamson drives, but both roads have since reopened.
Officials with Dominion Energy told ABC11 that it happened when an excavator hit a four-inch gas line.
They said crews are on site working to restore things to normal. Dominion said repairs could take seven to nine hours.
"There are numerous challenges to securing natural gas flow and multiple methods to it. Our primary goal is determining the safest way to do it under a particular set of circumstances and how to make it least impactful to those that depend on our service. "
Dominion said it is bringing in "additional resources to help us do the work as quickly and safely as possible."
They said about 20 customers lost their natural gas service.
Chopper11 HD was over the scene as businesses and homes nearby were evacuated.
Thomas Construction, which is working on apartment building construction in the area, told ABC11 that the leak is not related to their work, and said another contractor was doing some digging in the area.
An estimated time for the completion of repairs is not available, Raleigh Police said. Drivers are advised to avoid the area if possible until normal traffic flow is resumed.