A teenager fatally stabbed a 15-year-old boy in a busy park with a "terrifying" hunting-style knife, a court has heard.
Elton Gashaj was stabbed three times in Salt Hill Park, Slough, in September 2019.
Reading Crown Court heard a fight broke out between Elton and the defendant, who was also 15 at the time.
The defendant, 15, who cannot be named for legal reasons, denies murder and claims he was acting in self-defence.
Jurors heard Elton sustained "catastrophic" injuries when he was stabbed with the 19cm-long blade on 21 September at about 18:30 BST.
Members of the public had seen a group playing about with pampas grass stalks in the park, before a fight began between Elton and the accused.
Pavlos Panayi QC, prosecuting, told the court: "The fight quickly escalated into serious violence and the defendant produced that big knife and stabbed Elton three times in the upper body.
"Twice in the left hand side of the chest and once in the back.
"Those stab wounds, particularly one to the chest, caused him to collapse and bleed and he died very soon afterwards," he said.
The court heard the defendant received a cut to the chest and back, but that there was no "clear evidence" Elton had a knife or caused those injuries.
Jurors also heard the accused disposed of the knife in a bush in the park, before going to a relative's house and handing himself into police on 22 September.
After handing himself in, the defendant's injuries were deemed to be "superficial" by medical staff, Mr Panayi said.
The court heard he then answered "no comment" in a police interview a day later but claimed in a statement Elton stabbed him first and he had acted in self-defence.
Jurors heard that a second knife was found in bushes nearby with Elton's blood on it in October, and that the defendant had carried a knife for five weeks before the attack because he had previously been attacked himself.
Mr Panayi added: "Even if Elton had a knife, when the defendant took that weapon and plunged it once, and then twice, and then three times into the body of Elton Gashaj, [the defendant] went beyond anything which could be regarded as necessary or reasonable."
The defendant has admitted one count of possessing a bladed article.
The trial continues.