The incident happened in Camden Road near Walters Road at around 1.30pm today (April 2).
Officers and London Ambulance Service crews attended and found two 17-year-olds who were stabbed.
They were treated at the scene before being taken to hospital where their conditions are not known.
No arrests have been made but Camden Road remains closed by a crime scene with police asking people to avoid the area to reduce congestion.
The AA reports that Caledonian Road is also closed with bus routes 17, 91, 259, 393 and N91 diverted.
London Ambulance Service has been contacted for details but has not yet responded.
A Metropolitan Police spokesperson said: “An investigation has been launched after two teenage boys were stabbed outside an address in Camden Road, Islington at 13:33hrs on Tuesday, 2 April.
“The boys – both aged 17 – were treated at the scene and taken to hospital by the London Ambulance Service.
“They remain there for treatment and we await an update on injuries and condition.
“No arrests have been made at this stage. Camden Road is closed – please avoid the area to minimise congestion.”
