An air ambulance arrived just after 2pm at South Park, South Park Drive.
A London Ambulance Service spokesman said: “We were called just after 2pm to an incident at an address off Green Lane.
“We sent a single responder in a car, an ambulance crew and an air ambulance.
“Staff treated one patient, a teenage boy, who was taken as a priority to the Royal London Hospital in a ground ambulance.”
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