The fatal stabbing of a teenage girl in an east London park had "nothing to do with drugs but everything to do with an ambush," a court has heard.
Jodie Chesney, 17, was knifed in the back on 1 March as she chatted with friends in Harold Hill.
In his closing speech, prosecutor Crispin Aylett QC told the Old Bailey jury Jodie was "a victim of a brutal act of unprovoked violence".
All four defendants, aged between 16 and 20, deny murder.
Mr Aylett said Jodie's death was "but another example" of the "terrible consequences of the carrying and using of knives".
He added: "It seems every day now in our city, another young life is lost to a knife.
"I am sorry to say that your verdicts in this trial will not bring this to an end."
Manuel Petrovic, 20, from Romford, Svenson Ong-a-Kwie, 19, from Collier Row, a 16-year-old boy and a 17-year-old boy have been on trial since September.
Mr Aylett said all four defendants had "drifted into a life of crime whether stealing motorbikes or drug dealing".
On the night Jodie died, Mr Ong-a-Kwie "urgently" asked Mr Petrovic for a lift from Collier Row to Harold Hill, the jury was told.
Mr Petrovic drove the group in his black Vauxhall Corsa to Retford Road and waited while Mr Ong-a-Kwie and the 17-year-old went into Amy's Park.
"This was an ambush," Mr Aylett added: "The car need to be turned around so they could get away quickly.
"We now know the two in the park were Svenson and the boy, I say now know because the police were not told this before."
The trial continues.