The incident happened in High Road just after 5pm yesterday (October 9).
Officers arrived with paramedics who treated the teenager before taking him to hospital.
It has since been confirmed that he is in a life-threatening condition.
There have been no arrests but an investigation into the incident has been launched.
A Met Police spokesperson said: “On Thursday, 9 October at 17:03hrs police were called to reports of a shooting at High Road, Arnos Grove.
“Officers attended alongside the London Ambulance Service who treated a 17-year-old boy before taking him to hospital. His condition is believed to be life-threatening.
“No arrests have been made at this stage. We understand this has caused concern in the community and there will be an increased police presence in the area.
“An investigation has been launched and anyone with information that may assist police is asked to call 101 quoting CAD 5749/09OCT25.”
