A bright 16-year-old boy was stabbed in the heart on his way home from school as other children filmed on their phones.
It is claimed footage of the fatal attack on Irfan Wahid - apparently in a trivial spat over a girl - was uploaded by the pupils to the messaging app Snapchat.
Police have launched a murder inquiry and last night arrested a 16-year-old in connection with the killing, which took place on a busy high street in Leeds on Friday afternoon.
One school friend of Irfan suggested the stabbing had happened because the year 11 pupil had spoken to a friend's 'crush'.
Irfan had just got off the bus on his journey home from Carr Manor Community School when the attack happened, six streets from his home in Harehills, at around 3.40pm.
He had gone to get food with his brother and got into an argument with another teenager - whom he is believed to have known - before the knife was plunged into his chest.
Four friends carried Irfan away down the street, but he collapsed, bleeding heavily from the deep wound. He was taken to hospital in an ambulance and died shortly afterwards.
A local shopkeeper who saw the aftermath of the stabbing, said: "I was in the shop and heard a scream so I looked out and saw a boy who seemed to be bleeding from the abdomen.
"He met him, they fought and then he was stabbed and killed.
"It was his friend who stabbed him. Irfan was basically stabbed for talking to the girl his friend liked - it's shocking really." The teenager added: "I saw that people had filmed the attack - but I haven't seen any [footage]. My friend said that people had uploaded it to Snapchat, but I haven't seen it."
Yesterday Irfan's uncle, writing on a Facebook page set up after the boy's death, said: "No one can understand my pain. That empty space will always be there, we will be waiting for you come back home.
"Only memories are left behind. No words can describe how we feel. I love you so much nephew. Each time I close my eyes you're there and every youngster that walks past resembles you."
Tahir Fazil, another uncle, said Irfan was "brutally stabbed ... in the heart."
"Some of his friends were trying to carry him down the street but when they were near the bank he collapsed."
A 16-year-old friend of the victim said: 'Irfan had been talking to a girl at school and then his mate found out.
"Irfan had got off the bus to meet his brother and then got a text to meet his best friend somewhere.
Results of a post-mortem examination conducted on Saturday confirmed that the schoolboy died of a 'single stab wound to the chest'.
Yesterday another boy, aged 16, was arrested on suspicion of the killing and remained in police custody last night.
The day before a 15-year-old boy had been arrested on suspicion of murder, but was released without charge.
Police and family members of Irfan, whose father is a baker, asked witnesses to come forward with any video footage of the attack so it can be used as evidence.
A spokesman for West Yorkshire Police said: "Officers were called to Harehills Lane at 3.42pm. The injured male was taken to hospital but died a short time later.
Detectives investigating the murder in Harehills, Leeds, have confirmed the identity of the deceased as 16-year-old Irfan Wahid, following formal identification of the body today.
"This tragic incident happened in a busy area at a busy time of day with large numbers of people going about their daily business. It is also possible that people may have recorded footage on their mobile phones and I would again encourage those people to come forward."