Yang Jia was born on August 27, 1980, in Beijing, China. He was described as a quiet and reclusive man who had been unemployed and living in the capital city before the murders. According to media reports, Yang lived alone and kept to himself. In October 2007, he was arrested by the Shanghai police for riding an unregistered bicycle. Yang later testified in court that during the arrest and interrogation, he was insulted and physically assaulted, leaving visible bruises. Deeply affected by the experience, he attempted to sue the police for mistreatment, but his lawsuit was unsuccessful. That unresolved grievance, paired with growing frustration and a perceived lack of justice, appeared to fuel his eventual act of violent retaliation.

By 2008, Yang had become deeply disillusioned with the authorities. Some reports described him as socially isolated, with no stable job or strong social ties. Though quiet, his later actions suggested deep internalized rage and a sense of injustice. His resentment against the Shanghai police would eventually culminate in one of the most shocking revenge attacks in modern China, which drew widespread public attention and polarized national sentiment.

On July 1, 2008, the anniversary of the founding of the Chinese Communist Party, Yang Jia carried out a brutal and symbolic attack at the Zhabei District police station in Shanghai. At around 9:40 a.m., he threw eight petrol bombs at the gate of the police station and stabbed the security guard, Gu Jianming, who tried to stop him. Armed with a knife, Yang then stormed inside the building and began stabbing unarmed police officers in the lobby, duty room, and as he moved upstairs to the 21st floor. In total, he stabbed nine officers, six of whom died from severe injuries to vital organs including the lungs, necks, and livers.

Yang carried not just a knife but also a hammer, a dust mask, tear gas spray, and additional weapons—indicating premeditation. The victims were all male, long-serving officers, and members of the Chinese Communist Party. The murdered officers included Ni Jingrong, Fang Fuxin, Zhang Yijie, Zhang Jianping, Xu Weiya, and Li Kenan. The attack shocked the nation, especially because it was carried out inside a government facility.

Yang was immediately arrested at the scene. His trial, held behind closed doors at the Shanghai No. 2 Intermediate People's Court on August 27, 2008, lasted only about an hour. Four days later, on August 31, he was found guilty of premeditated murder and sentenced to death. His appeal was also handled in a closed court on October 20, 2008, where the judges upheld the death sentence and confirmed that he was of sound mind. Despite growing public calls for a mental health evaluation, the Supreme People's Court of China affirmed the ruling. On November 26, 2008, Yang Jia was executed by lethal injection.