Five school pupils from northwestern China have been detained after a 14-year-old classmate was beaten up so badly that he died. The pupil from Weihe Junior Middle School in Longxi county, Gansu province, died in hospital hours after he was attacked by classmates in an alley outside the school on Tuesday last week, local police said on Tuesday. The assault was sparked by a “trivial thing”, the police said in a statement issued on the social media platform WeChat, without giving further details. The victim, surnamed Zhang, did not dare tell teachers about the beating and he was only sent to hospital two hours later after a teacher noticed something was wrong, Red Star News reported. The police said Zhang was attacked during the school’s lunch break and Zhang’s mother told Red Star News that she was notified by the school around an hour later. Murder in the late afternoon: safety debate over killing of Chinese woman out on a keep-fit walk “When we arrived at the school, he was vomiting and lost consciousness,” she said. The boy was taken to hospital later that afternoon, but doctors said he had suffered brain damage and they did not have the facilities to treat him. He was transferred to a larger hospital in Lanzhou nearly four hours later, where he was declared dead, his mother said. A check-up by the Lanzhou hospital showed that besides brain damage, Zhang also suffered injuries to both lungs and a broken bone in his chest. The report said there were onlookers when the assault occurred, but no one called the police. Chinese police get top credit for Avengers: Endgame cinema stake-out The five attackers – whose ages are unknown – are now in police custody as the investigation continues. People under the age of 14 cannot be held criminally responsible under Chinese law, while those between 14 and 16 are only responsible for serious offences such as murder and rape. Bullying at schools has come under intense public scrutiny over the past two years, ever since two primary school students in Beijing locked a classmate in the toilet and threw a bin with used toilet paper over his head. The case triggered a national debate after the victim’s parents wrote about the incident online. In November, Guangdong education authorities took the lead in clamping down on school bullies by issuing new regulations with tougher punishments, ranging from school detention and expulsion to criminal liability.