An argument that began in an online discussion group evolved into a physical fight when the opponents met in person to continue their dispute.

A video surfaced on social media on Wednesday showing two men tussling at a bus terminal in Siu Sai Wan on Hong Kong Island on Tuesday night, Headline Daily reported.

It was understood that a 44-year-old man surnamed Cheng, said to be a volunteer who helped animals, had an argument with another man on the discussion group about animals early in the morning.

The two men then agreed to meet up in the evening in Siu Sai Wan for further discussion.

The video showed that Cheng, wearing a white vest and a pair of slippers, met the other man, said to be around 50, who was wearing a short-sleeve shirt and accompanied by a female friend who was wearing a face mask.

The two men continued another round of argument at the bus terminal. However, the verbal argument turned into a physical fight.

After the pair tussled, the second man suddenly pulled out a flashlight from his pocket and hit Cheng on his head.

Cheng, his head bleeding, ran to a convenience store nearby and grabbed a glass bottle, apparently planning revenge. However, the attacker and his female friend had fled.

Police arrived and sent Cheng to Eastern Hospital for treatment of his injury, Apple Daily reported.

Police classified the case as assault occasioning actual bodily harm and were hunting the suspect based on video footage taken by passers-by at the scene.