George Street was closed to vehicle traffic between King and Meeting streets after a contractor cut a natural gas line with a backhoe, authorities said.
College of Charleston Fire and EMS Chief Rick Krantz said the gas line was cut about 2:50 p.m. by workers who were preparing a vacant lot to be a parking lot for the college's new arena.
"There were markings showing where the utility lines were but this line wasn't marked," Krantz said.
The lot was the site of a Chinese restaurant before it was purchased by the college, he said.
No one was injured. Workers from SCANA responded and cappped the leak.
Krantz expected the street to be opened to traffic by 4:30 p.m.