Firefighters have been called to reports of a gas leak on The Cut in Waterloo.
An 18 inch gas main has ruptured in the roadway. Around 400 office workers and 200 people from a theatre, have been evacuated as a precaution.
A London Fire Brigade spokesperson said: "The road is closed from the junction of Baylis Road and The Cut down to the junction of Waterloo Road and Gray Street.
"Motorists and pedestrians are asked to avoid the area."
The Brigade was called at 1421 and are currently still on scene. Three fire engines and around 15 firefighters from Dowgate, Lambeth and Euston fire stations are in attendance.