A gas leak in Hounslow at the western end of the High Street shut part of the town centre yesterday after electrical engineers put a hole through gas mains.
Shoppers began noticing the strong smell of gas near Bell Junction on Tuesday and police yesterday cordoned off a large area while an investigation was carried out.
Staff from 12 shops on Hounslow High Street were evacuated.
A spokesman for National Grid UK, said: "Workmen were there from 2.30pm till 7pm yesterday to repair a hole in our low pressure gas main, made by Scottish and Southern Energy.
"It was caused by a fault with their electrical mains.
"A temporary repair has been made and a full replacement will take place at the weekend."