Six fire engines and around 40 firefighters attended an incident on King's Road in Sloane Square.
Firefighters investigated smoke logging in the basement of a five-storey mixed-use building. They worked alongside multi-agency service partners but following investigation, no fire damage was discovered. The smoke logging is believed to have been caused by an electrical event outside the building. There were no reports of any injuries to members of the public.
Specialist Brigade officers were also in attendance after elevated readings of a chemical substance were detected in the basement by crews using specialist equipment. This is believed to have been linked to the electrical event. Crews ensured no elevated readings remained before leaving the scene.
Around 50 people were evacuated from the building and a 25-metre cordon was put in place as a precaution. Road closures were also in place and people were advised to avoid the area.
The Brigade was called at 1052 and the incident was under control by 1425. Firefighters from Kensington, Soho, Chelsea and surrounding fire stations attended the scene.