Four fire engines and around 25 firefighters tackled a fire on Ridley Close in Romford.
The fire affected three garden sheds. One man was taken to hospital by London Ambulance Service.
Control Officers took the first of 18 calls at 0940 and have mobilised crews from Harold Hill, Romford, Hornchurch and Dagenham fire stations to the scene. The fire was extinguished by 1200.
The cause of the fire is under investigation.