A construction worker cut into a gas line with a backhoe at around 11 a.m., said PG&E spokesman David Eisenhauer.
The leak snarled traffic on Ygnacio Valley Road between Wimbledon Road and Lennon Lane, temporarily shutting two westbound lanes and all eastbound lanes.
The leak occurred near NorthCreek Church at 2303 Ygnacio Valley Road and sent students at nearby NorthCreek Academy, a private school serving kindergartners through eighth graders, home for the day.
The gas line was fixed at about 5:30 p.m., PG&E reported.
The utility is investigating the break.
