Prominent Pro-democracy leader Joshua Wong and two others have been arrested by the police ahead of another weekend of planned protests in the Chinese-ruled city.
Mr Wong was pushed into a minivan while running errands in the streets of Hong Kong.
He has been taken to the police headquarters in the city.
Police say the arrest is on suspicion of “inciting others to take part in unauthorised assembly” among other charges.
Unrest in Hong Kong escalated in mid-June over a now-suspended extradition Bill that would have allowed people to be sent to mainland China for trial.