Four fire engines and around 25 firefighters were called to a fire at an office block on Cottons Lane in Southwark.
One laptop in a storage room on the second floor of an eight storey office building was alight. Around 700 people evacuated the building before the Brigade arrived.
The Brigade's 999 Control officers received their first call regarding the fire at 1136. They mobilised crews from Dockhead, Dowgate, Whitechapel and Old Kent Road fire stations. The incident was over by 1208.
The cause of the fire is under investigation.