A tooth for a tooth, an eye for an eye.
When a 36-year-old man heard from his daughter that her classmate had hurt her eye in school, he sought revenge.
Carrying a fruit knife, he went to look for the 10-year-old boy in a primary school in Zhejiang, China, on Sept 21 afternoon.
Moments later, the child was found lying in a puddle of blood on the bathroom floor. He had multiple knife wounds as well as a slash to his neck.
Police arrived at the scene and saw the boy's assailant smoking next to him with the weapon lying nearby.
The child succumbed to his injuries three hours after he was rushed to a hospital.
According to Chinese media, the parents of both children had agreed earlier to have the boy publicly apologise to the girl for injuring her during a quarrel.
The school dispute, however, took a drastic turn after the girl's father became enraged when she told him that her eye was hurting.
Local police said that the girl's injury was minor and did not hamper her ability to attend school.
"In what world do we kill children with knives?" the boy's father asked.
"My greatest wish now is that the law will severely punish the murderer and grant my son justice. My child died so unjustly."
The attack shocked many in the country, with some netizens calling the attacker's fatherly love "twisted" while others said that he shouldn't have overreacted to a quarrel among children.
The man has been detained for further investigations.
This incident follows a string of knife attacks in China's schools. A 29-year-old man killed two pupils at a Shanghai primary school in June while another 28-year-old man stabbed nine students to death and injured 10 others in a Shaanxi secondary school in April.