A 17-year-old girl was killed in a "terrible and cowardly" stabbing during a drug turf war, a court has heard.
Jodie Chesney was stabbed in the back while playing music and smoking cannabis with friends in a park in Harold Hill, east London, on 1 March.
She may not have been the intended target of the attack, the prosecution told the Old Bailey jury.
Manuel Petrovic, 20, Svenson Ong-a-kwie, 19, both from Romford, and two boys, aged 16 and 17, deny murder.
The jury was told two people came out of the dark in the park and the taller of them swung his right arm at Jodie's back.
She suffered a deep wound to her back and was left bleeding heavily as her attackers disappeared seconds later.
Jodie's boyfriend Eddie Coyle, 18, caught her as she fell and eased her to the ground, crying and screaming at Jodie to stay awake while holding her hand.
The first call to emergency services was made at 21:22 GMT and two police officers were on the scene within 13 minutes.
The ambulance set off for the Royal London Hospital but it was decided that doctors in a car should meet it halfway at an Esso Garage in Gants Hill.
They attempted to resuscitate Jodie on the forecourt of the petrol station, prosecutor Crispin Aylett QC said.
"Despite the best efforts of all concerned, there had been no cardiac activity for some time. Jodie was pronounced dead at 22:26," he added.
Mr Aylett told jurors none of Jodie's friends had any idea who was responsible for the "terrible and cowardly" attack.
Jurors were told the four defendants were involved in the supply of drugs and one or more of Jodie's friends had bought cannabis from those accused in the past.
"The drug-dealing world is one of turf wars, rivalries and pathetic claims for 'respect'," Mr Aylett said.
He said, however, that there was "nothing to suggest that Jodie was involved in the supply of drugs or that she might have upset anyone".
"If the prosecution are right in saying that Jodie Chesney was an entirely blameless individual who got caught up in some quarrel between drug dealers, then her murder was the terrible but predictable consequence of an all-too casual approach to the carrying - and using - of knives."
Following national publicity, police got a breakthrough when a witness reported two males getting into a stationary black Vauxhall Corsa.
Mr Aylett said Jodie's murder might have gone unsolved if not for the chance sighting by witness, Andrei Mihai, who reported seeing a stationary car near to the park where Jodie was stabbed and from where he heard screaming.
A couple of hours after the killing, a black Corsa registered to Mr Petrovic was found abandoned about two miles away, he said.
Following his arrest, Mr Petrovic, of Highfield Road, Romford, east London, admitted driving to Harold Hill with a friend and two others who had gone into the park to collect money and drugs.
He denied knowing the pair were armed beforehand, the court heard.
The trial continues.