A 15-year-old boy has died after being stabbed in west London.
Officers were called to reports of a fight on Blyth Road in Hayes at just before 8.35am on Friday.
The victim was found suffering from multiple stab wounds and died at the scene.
The Metropolitan Police said a suspect had been detained, but provided no further details.
Police commander for Hillingdon, Chief Superintendent Peter Gardner, said: “I am deeply saddened to hear of the tragic loss of a child’s life to knife crime in Hillingdon.
“This incident, that claimed the life of a 15-year-old boy, took place during this morning’s school run.
“A family has been devastated and the effects of this terrible incident will reverberate throughout our communities.
“As a parent of a teenage boy myself, I cannot imagine the pain the family is going through and I offer our full condolences and support.”
He added that police patrols in the area would be stepped up.
Formal identification of the victim has yet to take place and a post-mortem examination will be held in due course, the force said.
Cordons remain in place at the scene.
Anyone who witnessed the incident or has any information is asked to call police on 101, quoting reference Cad 1681/11Jun, or contact Crimestoppers anonymously on 0800 555 111.