She was repeatedly stabbed near the Whitgift shopping centre in Croydon, south London, after the attacker produced a knife from his pocket in a dispute over a bag, Sky News understands.

Police responded within two minutes and a 17-year-old boy, who is believed to have been known to the girl, has been arrested over the incident in Wellesley Road.

Witnesses told how a bus driver and a passer-by tried to save the life of the girl, who was stabbed at around 8.30am, while others chased the attacker.

Victor Asare, 50, told how he saw a boy stab the girl in the neck with a knife which was "black, thin and about a foot long".

"The boy wore a black blazer, the girl wore green. It looked like the girl didn't want the boy to come closer," said the security worker. "The blood was coming like water."

He said the boy ran away and "everybody was crying and screaming", adding: "The girl was on the floor.

"We tried to catch him and a lot of people tried to save the girl. I was so shocked, I was shaken. It's somebody's daughter."

Chief Superintendent Andy Brittain said at a news conference from the scene: "This is every parent's worst nightmare.

"I know the officers who responded this morning, along with our emergency service colleagues, are devastated at the victim's death. This is an emotion I share, and I know people across Croydon will be feeling the same."

A white forensic tent and a stationary number 60 bus were within the police cordon, while footage posted on social media showed police cars and ambulances surrounding the vehicle.

'Is my friend dead?'

Michael Fyffe told Sky News he was on his way to work when he saw a "commotion" and was told the girl had been stabbed.

He said: "There were loads of people who had just come off the bus and then I think two of the girl's friends came out and they were trying to rush over towards the body.

"So myself and a few of the other people tried to hold her back and just say, 'Look let them try and help your friend', and she was just screaming, 'Is my friend dead? She's my best friend'."

The girl was a pupil at the Old Palace of John Whitgift School, which last week announced it would close in August 2025.

In a statement, the independent girls' school said: "We are deeply shocked by the senseless and tragic death of our much-loved and valued friend and pupil.

"It will take some time for the Old Palace community to come to terms with this terrible news, and we will offer support to our pupils as we try to do so.

"Above all, we send our love and deepest sympathies to the girl's family at this unimaginably distressing time."

Girl's family 'devastated'

Police said the girl was pronounced dead at the scene at around 9.20am, while the suspect was arrested within 75 minutes of the stabbing in nearby New Addington and remains in custody for questioning.

James Watkins, from Mainz World, which runs prevention and intervention projects for children and young people, said he was supporting the girl's "devastated" family, who arrived on the scene between 9am and 10am.

"They were devastated and I would say more importantly in shock, I don't think it feels real for them," he said.

Mayor of London Sadiq Khan said he was "absolutely heartbroken" by the death.

"My thoughts and prayers are with this young girl's family and friends, and the whole community, at this unimaginably awful time," he said.

'Impossible to comprehend'

Met Police Commissioner Sir Mark Rowley said: "The senseless murder of a 15-year-old girl on her way to school is impossible to comprehend.

"It was moving and humbling to meet many members of the exceptional Croydon community who have come together in support of a family now dealing with the most unimaginable grief."

Croydon Council held a minute's silence at their cabinet meeting this evening and said: "Croydon's thoughts are with [the victim's] loved ones".

Croydon MP Sarah Jones, who attended the Old Palace school, said: "I'm heartbroken that a child in my town has been killed on her way to school and I cannot imagine the grief that her family will be going through at this time."

Anthony King, chair of the My Ends project, which works in the Croydon community to reduce crime, said: "The wider impact on school children and the community has been devastating."

Mayor of Croydon Jason Perry said: "We all personally feel devastated by the events that have happened here in Croydon this morning and the tragic loss of such a young life."

Donna Murray-Turner, chairwoman of the local Safer Neighbourhood Board, added: "The impact this has had on the community is immense. It is devastating that another young life has been taken and we the community stand with our partners and the family and honouring that grief and that morning."