Happy Pharrell Williams Download 'Happy' on iTunes
Detectives from Scotland Yard are investigating whether a murder and two stabbings in London yesterday happened during a clash between rival gangs.
Neighbours say a 17 year old was shot dead as he ran through a housing estate in Peckham trying to escape.
Police have arrested three people.
The victim was the 19th teenager to be killed in the capital this year. A total of 15 were murdered last year and 29 in 2008.