The death of a 17-year-old boy in Greenwich brings the toll of teenagers murdered in London this year to nine.
Murder squad detectives are probing what caused his fatal injuries at a house in Greenwich after a neighbour reported hearing a shot in the early hours.
Speaking yesterday, Metropolitan Police Commissioner Sir Paul Stephenson said it would be "foolish" not to be concerned about the level of gun crime in the city.
He said senior officers are concerned about the falling age of people involved in shootings, whether they are victims or gunmen.
Last Sunday, Wesley Sterling, 16, died after being repeatedly stabbed in the chest outside a birthday party at the Croydon Sports Arena.
The teenager, known locally by the nickname Solem, is thought to have been involved in a row after trying to gatecrash the event earlier in the evening.
Student Agnes Sina-Inakoju, 16, died from a gunshot wound to the neck after a shooting at a fast-food takeaway in Hoxton Street, Hackney.
Police said they were hunting two young men on mountain bikes who fired into the shop shortly after 7pm on April 14.
Student Aliza Mirza, 18, of Ilford, east London, died from a stab wound to the neck in Manor Park on April 3.
Godwin Lawson, a 17-year-old aspiring footballer, from Enfield, was stabbed to death in Hackney on March 27.
Sofyen Belamouadden, 15, from Acton, west London, was stabbed to death by a mob at Victoria railway station on March 25.
The teenager was attacked in the booking office of the Underground station during the afternoon rush-hour.
Rapper Isschan Nicholls, 18, of Poplar, east London, died after being stabbed in the stomach and leg when youths clashed in Bow on January 13.
Friends said Isschan, a former pupil of the Canon Palmer Catholic School in Ilford, was the victim of postcode gang rivalry.
Olukorede Fajinmi, 17, was fatally stabbed outside the Showcase Cinema in Beckton, east London, on February 19.
Detectives suspect the attack was linked to an earlier fight involving a group of youths a short distance away in the grounds of a five-a-side football venue.
Jessie Wright, 16, of Islington, north London, was found strangled in a derelict yard on March 4.
Zakk Sackett, 19, who may have been in a personal relationship with the victim, has been charged with murder.
The toll does not include the death of 12-year-old Ajit Singh-Mahal at his home in Barking, east London. His mother has been charged with murder.
Last year 14 teenagers were murdered in London, with 10 of them stabbed to death and one shot.
Police took action in 2008 after an explosion of teenage violence and have watched the number of attacks and murders among young people fall significantly.
Among the tactics used has been a huge increase in stop and searches, including the use of metal detectors at transport hubs, including Victoria railway station.