The incident, which was captured in a now-viral video, happened at the boy’s home in Nanjing on Saturday, according to local reports. According to police, the classmate’s 33-year-old father, identified only as Lou, went to the boy’s home to apologize after hearing that the boy had hit his son at school earlier in the day. Later in the conversation, however, Lou slapped the boy across the face, sending him flying off his stool and onto the floor. More from NextShark: Black, Asian and Hispanic Corps Associations Rally Like Voltron to Fight Attacks on Asian Americans The violent moment shook the boy’s 64-year-old grandfather, identified only as Zhu, who tried to defend the boy. The senior picked up the chair he was sitting on in an alleged attempt to hit Lou. In response, Lu pushed Zhu to the floor. The impact broke the elderly man’s leg, which then required medical treatment. The boy’s family reported the incident to the authorities. The next day, Lu was arrested on assault charges. More from NextShark: Watch: Hong Kong residents bid farewell to Jumbo Floating Restaurant as it is towed to secret location The investigation revealed that the feud at the kindergarten started when the boys fought over a toy on the playground. Zhu’s grandson reportedly scratched the back of Lu’s son’s head with the toy, resulting in a cut. Lu’s son suffered a cut in the fight over a game with his grandson Zhu. Image via Sohu News The mother of Zhu’s grandson reportedly intended to make her child apologize to Lu’s son later that night. According to information, both families live in the same community. More from NextShark: NYC Mayor Eric Adams cites Christina Yuna Lee’s death in bid to amend bail reform The incident has since gone viral on Chinese social media, garnering over 400 million views on Weibo alone. Several social media users condemned Lu, who was reported to be a doctor. The story continues The incident remains under investigation. Featured image via NetEase More from NextShark: ‘Cuppa With Kumi’ host reveals anxiety, fear of being targeted for racism during COVID-19 outbreak