London - Katie Rough was murdered with a Stanley knife, a court heard on Wednesday.
The news came as the 15-year-old girl accused of killing her appeared before magistrates for the first time.
Katie was found in a playing field dying from wounds to her neck and chest. Police have seized a knife and blades.
The 15-year-old defendant – who cannot be identified for legal reasons – showed no emotion as she appeared at York Magistrate’s court, watched by Katie’s family.
The girl has been charged with murdering Katie, and possession of an offensive weapon in a public place.
Looking pale and wearing a grey sweater, she stared straight ahead from the glass-panelled dock of the Victorian courtroom throughout the eight-minute hearing.
A group of Katie’s relatives watched the proceedings quietly.
They included her grandparents, aunt and uncle and brother Jack, who all left without comment.
Prosecutor Catherine Turnbull said police received a 999 call at 4.27pm on Monday, and traced it to Alness Drive in the Woodthorpe area of York.
She added: "Police were contacted to attend the location and found Katie was in a football field at the end of the road."
The victim’s mother Alison Rough, 38, also called police at 4.50pm to tell them Katie was missing and had not been seen for 45 minutes.
Residents told how Mrs Rough arrived in the street as police were tending to her daughter.
She fell to her knees and sobbed: "No, no – it’s my little girl."
Mrs Rough was joined by her husband Paul, 34, as emergency services fought to save Katie, who died later in hospital.
The defendant’s solicitor made no application for bail and she was remanded in custody to appear at Leeds Crown Court tomorrow. A fundraising page set up by York resident Maggie Jackson to provide financial support for the family passed £6 000 (about R99 000) within 24 hours.
Admitted she did not know the family, Miss Jackson wrote: "No mother should be going through what Katie’s mum is having to deal with – breaks my heart.
"Really saddened me, I can’t stop thinking about what her mum and family will be going through. It has shocked the whole of York.
"I don’t know if it’s too early to say this but I’d like to raise money to give to her family to help them through this terrible time without any other worries.’
On Wednesday night, more than 550 people had donated up to £50 each as the fund exceeded £7 500.
Writing on the Go Fund Me page, Katie’s brother Kieran Hudson, 18, said a ‘huge thank you’ to those who donated, adding that it was ‘hugely appreciated’ by the family.
Katie’s aunt Janice Hinds, 40, wrote: "Just wanted to say thank you to everyone who has donated. The generosity of strangers is overwhelming."
Paying tribute to the schoolgirl, several family members also posted photographs of Katie, showing her playing the guitar and paddling in the sea.
Alongside a picture of her as a bridesmaid at her parent’s wedding just weeks ago, her grandmother June Ferguson, 62, wrote on Facebook: "Our beautiful princess who is now an angel."
Her uncle, Mark Hinds, 42, shared a police post naming the schoolgirl with the message: "RIP Katie – we are all devastated and love * lots."