Six fire engines and around 40 firefighters tackled a fire at an office building on Ley Street in Ilford.
The roof of the single storey building was destroyed by the fire. Around 20 people left neighbouring properties before the Brigade arrived.
One of the Brigade's 32-metre turntable ladders was used as an observation tower, providing the Incident Commander with an aerial view of the fire and aiding their decision-making.
Control Officers took the first of seven calls at 0353 and mobilised crews from Barking, Stratford, Dagenham and surrounding fire stations to the scene. The fire was extinguished by 0511.
The cause of the fire is under investigation.