The boy left the “innocent and helpless” girl, who was 13 at the time, with life-threatening injuries following the “horrific and unimaginable” attack in November, Humberside Police said.
The force added that the girl, now 14, appeared at the side of the A63 near the Humber Bridge in Hessle, East Yorkshire, on 1 November 2024 with multiple injuries and asking for help from motorists.
She had severe injuries to her neck, abdomen, chest and back, and was in hospital for three weeks.
The girl is still recovering from both the “physical injuries” and the “mental scars from that night” and is “lucky to be alive”, Detective Superintendent Simon Vickers said.
The senior detective, who led the investigation, added that the boy went on the camping trip with “one intention” and that was to “attempt to kill an innocent and helpless young girl”.
DS Vickers said the teenagers were part of a group that had arranged to go camping before there was an argument.
He continued: “Feeling unwelcome, the teenage girl became uncomfortable and decided that she was going to leave. when one of the boys offered to walk her through the wooded area.
“Her attacker then pursued the pair, insisting that he would walk with her, and the other teenager returned to the camp site.
“What the girl didn’t know was that he intended to stab her.”
DS Vickers added that the girl saw the 15-year-old pull a katana, a Japanese sword with a curved, single-edged blade, from the waistband of his trousers after pretending to go to toilet.
The girl then attempted to flee to safety before the boy pushed her to the floor and repeatedly stabbed her, the senior detective said.
Officers later recovered the katana from one of the tents near to where the girl was found.
DS Vickers said one of the girls on the camping trip had taken the sword from a relative’s knife collection and this was passed around the group before the teenage boy used it in the attack.
The defendant, who cannot be named due to his age, was found guilty of attempted murder by a jury in March.
He was sentenced to 11 years’ detention and handed an indefinite restraining order.
The defendant had denied attempted murder but pleaded guilty to grievous bodily harm and possession of a bladed article.
Read more:
Prince Harry responds to charity row
New photos show moment of North Sea crash
Drug dealer admits killing boy in cannabis gummies lab blast
Humberside Police said three teenage boys, aged 15, 16 and 17, and a 14-year-old girl were subsequently released without charge in connection with the attack.
A 16-year-old girl, who cannot be named due to her age, was charged with possession of an offensive weapon and appeared at Hull Youth Court in February.
She was sentenced to a nine-month youth referral order and ordered to pay a £111 fine, the force said.
After the boy was sentenced, Mr Vickers said: “This was a camping trip which should have been an enjoyable experience for everyone involved and the events that unfolded that night, leaving a young girl in a life-threatening condition, should have never happened.
“The boy went on that camping trip with one intention and that was to attempt to kill an innocent and helpless young girl, and because of him she is lucky to be alive following what I can only describe as a horrific and unimaginable attack.”
He added: “Whilst the boy is now being punished for his unforgivable actions, there are no winners in this situation, with both teenagers’ lives now having changed forever.
“Carrying any form of knife, whether you intend to use it or not, is never OK and not something we as a police force will ever accept as we continue to do everything we can to tackle knife crime across our force area.”
