A murder investigation was launched after a teenager was fatally stabbed last night, police said today.
Officers discovered the 17-year-old boy after they were called to reports of a fight outside the Showcase Cinema, in Beckton, east London, at 8.45pm.
The youth, who was suffering from a stab wound, was pronounced dead at the scene.
Two more teenagers - aged 15 and 16 - were arrested nearby and taken into custody.
They remained at separate east London police stations today.
The victim has yet to be formally identified. Next of kin were being informed.
A post-mortem examination is due to take place at 1pm at East Ham Mortuary, Scotland Yard said.
Detective Inspector Ian Goldsborough, the investigating officer from the Homicide and Serious Crime Command (HSCC), said: "We believe there will have been people in the area, either going to or from the Showcase cinema or the nearby restaurant, that may have seen or heard the incident that has lead to the tragic death of a teenager.
"We are appealing to them, or anyone else that was in the area at the time of the incident to contact us and lets us know what they saw or heard."
Officers were keeping an open mind as to a possible motive.
Anyone with any information should call police on 020 8345 4142 or Crimestoppers on 0800 555 111.