Six fire engines and 35 firefighters and officers were called to a fire in the gym of a derelict hospital on Cotswold Road in Sutton this afternoon.
Part of the ground floor was damaged by the blaze.
The Brigade was called at 1550 and the fire was under control by 1638. Fire crews from Sutton, Wallington, Mitcham and New Malden fire stations were at the scene. The cause of the fire is under investigation.