A murder probe has been launched into the death of a teenager who died after he was found wounded in the front garden of a suburban home following a reported fight.
Officers were called to Empress Drive in Chislehurst, south-east London, shortly after 9pm on Tuesday and found the 18-year-old victim injured.
He was taken to a south London hospital where he later died shortly after 8am on Wednesday.
One neighbour, Marian Pammenter, said she saw paramedics attempting to save the teenager's life but heard no signs of a fight beforehand.
The 83-year-old said: "We saw the young chap taken into the ambulance, they were working very hard on him.
"We don't know what happened, we think he came through the alleyway and collapsed in the front garden.
"There was nobody else chasing him.
"There was no sign of a fight or shouting.
"We were so sad they could not save him."
A post-mortem examination has yet to take place and the victim has not been formally identified but his next of kin have been informed.
Scotland Yard said there have been no arrests and officers are appealing for witnesses.
Detective Chief Inspector Tim Wright, of the Met's Homicide and Major Crime Command, said: "We understand that neighbours and people passing through the area witnessed the incident on Tuesday evening.
"We are keen to speak to all witnesses and would encourage them to come forward as soon as possible.
"A young man has lost his life and we are doing everything we can to piece together what took place."