A 15-year-old boy has been stabbed to death outside a McDonald's restaurant in east London.
Officers were called at 3.20pm and said the boy was attacked either on a bus or shortly after he got off, close to Stratford Centre mall.
His friends "came to his aid and members of the public provided first aid at the scene", DCI Chris Soole said.
An air ambulance was dispatched but the boy was pronounced dead at the scene at 3.49pm.
A witness said the victim was "all covered in blood" and was "in pain and tried getting up".
They continued: "There were people around gathering. It was scary as you did not know if any of them could have had a knife, too."
Another witness said the victim was "a young guy", adding: "I think the ambulance guys tried to give him first aid."
His next of kin have been informed and a post-mortem will be held to establish cause of death.
A second 15-year-old boy was also found with stab injuries and taken to an east London hospital. His injuries are not life threatening, police said.
There are no arrests as yet.
CCTV is being analysed and forensic analysis is taking place.
The shopping centre tweeted that it had closed following the incident.
Appealing for witnesses, DCI Soole said it was a "very busy area and lots of people would have been out on the school run or making their way home".
Anyone with information should call 101, quoting CAD 4644/01OCT19. Alternatively, they can ring Crimestoppers, anonymously on 0800 555 111.