Six fire engines and 35 firefighters and officers were called to a fire at a doctors surgery under refurbishment in Claremont Road, Walthamstow this afternoon.
Part of the first floor of the building was damaged by fire and the roof was gutted in the blaze.
The Brigade was called at 1509 and the fire was under control at 2009. Fire crews from Walthamstow, Tottenham, Leyton, Woodford and Hornsey fire stations attended the scene.
The fire is believed to be accidental.