Firefighters were called to St James Street in Walthamstow to reports of a crane colliding with a bridge.
Crews released one man from the cab of the crane, who was trapped by his injuries. He was taken to hospital by London Ambulance Service crews.
The Brigade was called at 1232 was the incident was over for firefighters by 1347. Two fire engines from Walthamstow Fire Station and two fire rescue units from Edmonton and Islington fire stations attended.