An 18-year-old man was stabbed to death near a bus garage in Walthamstow, east London, in the early hours, Scotland Yard said today.
Officers on routine patrol saw two or three males running away from a grassy area at 1.40am, according to the Metropolitan Police.
They then discovered a man suffering from a stab wound.
A police spokesman said: "The victim - believed aged 18 years - was taken by London Ambulance to Whipps Cross Hospital.
"He was pronounced dead shortly after arrival.
"We believe we know the identity of the deceased, but await formal identification and confirmation that all next of kin have been informed."
A post-mortem examination and inquest will be arranged in due course.
Two youths were arrested near the scene off Selborne Road and are in police custody, the Met said.
Acting Detective Chief Inspector John Sandlin said: "I am appealing for anyone who was in the area at the time of the murder to please contact police with any information you may have. The incident happened close to a well lit bus garage in Walthamstow Central."
One of the two arrested - a 17-year-old - received hospital treatment for a minor slash wound to the arm before being taken to an east London police station.
The other person arrested, in his late teens or early 20s, was also taken to an east London police station, police said.
Anyone with information is asked to call the incident room based at Barking on 0208 345 3715 or Crimestoppers anonymously on 0800 555 111.