Police were called to the incident at 4.38pm yesterday (Tuesday) on Moorside Road.
Emergency services attended the scene and a five-year-old boy was taken to hospital for treatment.
His injuries are not believed to be life threatening.
There have been no arrests at this stage.
A spokesperson for the Metropolitan Police said: “Police were called at about 16:38hrs on Tuesday, 13 August to reports of a child fallen from height on Moorside Road, BR1.
“Officers, the London Ambulance Service and London’s Air Ambulance attended.
“A 5-year-old boy was taken to hospital for treatment.
“His injuries are not believed to be life threatening.
“There have been no arrests.”