According to Truong Minh Khanh, chairman of Hau Nghia Town, the case happened on Thursday in the town when Le Hoai Bao, 28, took his son to a local park. 

While the father and son were playing hide and seek there, a nearby female lottery seller thought that Bao was trying to kidnap the boy. So she loudly shouted for help.

At that time, Nguyen Ngoc Hai Dien, 26, rushed to catch the boy. Although Bao explained that that was his son and they were playing with each other, Dien, however, remained angry and ignored Bao's pleas.

Dien suddenly ran into a restaurant near the park and grabbed a knife which he used to stab Bao in his chest.

Despite being taken to hospital immediately, Bao died after being stabbed in the heart.

Dien has been detained for further investigation.