Firefighters were called to reports of a gas leak on Upper Ground on South Bank.
A six-inch gas main in the basement of a television studio under refurbishment had ruptured. There were no reports of any injuries.
Station Commander Matt Williams, who was at the scene, said: “Road closures were in place whilst firefighters worked with partners to isolate the gas leak and make the scene safe.
“Around 90 people were evacuated from the site and neighbouring properties and a 25 metre cordon was put in place as a precaution.”
The Brigade was called at 1727 and the incident was over for firefighters by 2135. Three fire engines from Dowgate, Soho and Tooting fire stations and three fire rescue units from Euston, Bethnal Green and Bexley fire stations attended the scene.