A 17-year-old male has been arrested on suspicion of murder.
A 28-year-old man has been arrested on suspicion of attempted murder.
Both arrests took place on the morning of Sunday, 13 December.
A 25-year-old man arrested on Saturday, 12 December has been released and no further action will be taken against him.
Police were called at approximately 6.50pm on Friday, 11 December to Woodman Street, North Woolwich.
Officers and London Ambulance Service attended and found a 15-year-old male who had been stabbed. Despite the efforts of the emergency services, he was pronounced dead at the scene.
His next of kin have been informed.
Detective Chief Inspector Mark Wrigley of Specialist Crime Command (Homicide), said: “These arrests are a positive step in our investigation but we are still working to establish exactly what took place on Friday night.
“There were lots of people in the area at the time and I would appeal for anyone who hasn’t yet come forward, to do so. The senseless killing of a 15-year-old has understandably shocked the community and I would urge them to help us bring those responsible to justice.”
The investigation is being led by the Met’s Specialist Crime Command (Homicide). Anyone with information is urged to call the incident room on 0208 345 3715.
Alternatively, they can contact the independent charity Crimestoppers, anonymously, on 0800 555 111.