Three people have been arrested after a teenager was stabbed near a park.
The Metropolitan Police said officers were called to North Street in Barking, east London, at 7.24pm on Monday following reports of a stabbing.
Police and the London Ambulance Service rushed to the scene, near Barking Abbey Grounds, where they found a male, believed to be 17, suffering from a stab wound.
The teenager was taken to hospital, where his condition is believed to be life-threatening, the Met added.
A police cordon manned by uniformed officers was in place around a large area of the park between St Joseph's Primary School and St Margaret's Church on Tuesday morning.
Three people have been arrested in connection with the incident and remain in custody, the force said.
Inquiries continue to establish the full circumstances surrounding the stabbing, Scotland Yard added.
Witnesses should call the police on 101, quoting ref 6440/11nov.