An 18-year-old has been stabbed to death in Twickenham in broad daylight in front of several witnesses.
In a statement, Met Police said the teenager was murdered in Richmond yesterday afternoon at around 4:45pm.
The young man was attacked and stabbed repeatedly on Craneford Way Playing Fields in Twickenham, south west London.
Police said the incident took place in broad daylight and open view of the park, and it is understood that it was witnessed by a number of people.
Met officers were called at 4:45pm to Craneford Way and the teenager was pronounced dead in hospital at 5:54pm.
No arrests have been made at this stage.
Detective Chief Inspector Vicky Tunstall said: "The incident occurred in a playing field area and was witnessed by a number of people.
"Some of those people are believed to have filmed events as they unfolded; I ask that any videos are not shared via social media to avoid causing the young man's family any more distress at this already incredibly difficult time for them.
"Instead, please go to the police immediately. A number of people have spoken to us, but we need to hear from anyone who has information that could help.
"We're working to establish the motive behind this tragic incident and following a number of leads. If you believe you can help us, then please make contact."
Chief Superintendent Elisabeth Chapple, commander for policing in south-west London, said: "Our thoughts are with the young victim and his family at this awful time.
"No young person should lose their life in London and we will do all we can to support our colleagues with their investigation.
"Local residents can expect to see an increased police presence in the area.
"If anyone has any concerns, or information that could help, I encourage them to contact those officers and tell us what they know."
Witnesses are urged to contact police on 101 quoting: CAD 5697/12OCT.