A teenager has been stabbed to death near Stratford Shopping Centre.
Officers found the 15-year-old boy suffering from stab wounds on Stratford Broadway in east London shortly after 15:20 BST on Thursday.
Police believe he was either attacked on a bus, or shortly after getting off.
A second teenager, also 15, was found with stab injuries which are not believed to be life-threatening. Scotland Yard said no arrests had been made.
Det Ch Insp Chris Soole said the boy was stabbed during an altercation “on or shortly after alighting from a bus which stopped very close to Stratford Shopping Centre”.
He added: “The victim of this stabbing was a schoolboy with his whole life ahead of him. He had everything to live for.
“This was a senseless attack and we share the concern and alarm this murder will no doubt cause in the local community.”
In a separate stabbing about five hours later, an 18-year-old man was knifed to death in south London.
Police found the man suffering from stab injuries on the Brandon Estate in Camberwell, at about 20:20 BST.
He was pronounced dead at the scene an hour later and no arrests have been made.
The Stratford victim’s friends and members of the public provided first aid but he died at the scene at about 15:50, police said.
The teenager’s next of kin have been informed, and the second boy who was stabbed remains in an east London hospital.
A Section 60 order has been implemented, giving officers increased stop and search powers across Newham.
Police have closed off a large part of Broadway, and the shopping centre entrance nearest Stratford Station has also been closed.
One witness said the attack happened outside a McDonalds restaurant.
“At that moment there were not many people around him so I could see him all covered in blood. He was in pain and tried getting up,” they said.
“There were people around gathering. It was scary as you did not know if any of them could have had a knife too.”