Isaac Cheng, vice-president of Demosisto, was assaulted near his home in Tai Wai by three men.
He was repeatedly beaten on the face and lost his glasses. He was taken to a hospital by members of Demosisto.
Cheng also defended the planned boycott, rejecting criticism that they are too young to make such a decision.
Cheng said he believes high school students are mature enough to decide whether they want to join or not. He added that nearly 20,000 students took part in their survey of the issue and made judgments on their own.
More details to follow.
BREAKING: Our vice chairman @IsaacChengCKL was just assaulted near his home in Tai Wai by three men. He was repeatedly punched in the face and lost his glasses. Our members are now accompanying him to a hospital check-up. More details to follow.
— Demosistō 香港眾志 (@demosisto) September 2, 2019