A video circulating on social media showed a man giving flowers to Junius Ho and asking permission for a photo with him. The man then drew a knife from his bag and stabbed Ho in the chest but was quickly overpowered by the victim and several others.
Pro-government rally, called "Safeguard Hong Kong," comes ahead of another protest planned against the government's handling of the now-suspended extradition bill that would have allowed people in Hong Kong to be sent to mainland China for trial.
Andy Chan, heading the fringe Hong Kong National Party, was invited to give a talk but his invitation sparked stern criticism both from Beijing and authorities in the city. China demanded the event be scrapped, but the club decided to press ahead.