Officers also fired at least two bean bag rounds from elevated positions at the station, after protesters threw objects towards the station and shouted abuse at officers.
Some journalists were pepper-sprayed, along with protesters after police rushed to confront dozens of demonstrators who had been chanting and aiming laser pointers at the station.
A woman dressed in black was confronted by journalists and protesters who demanded to know whether she was an undercover cop, after she was spotted holding a baton next to a group of officers wearing police vests who subdued a protester.
She did not respond, but one of the officers identified himself as the team leader, and said she was indeed one of his colleagues, before the group left the scene.
Several other people were subdued and detained.
Demonstrators had repeatedly tried to block traffic on the intersection of Nathan Road and Prince Edward Road West, outside the Mong Kok police station, by placing debris in the road and setting it on fire.
Police had issued repeated warnings for them to disperse, adding that they were taking part in an illegal assembly.
Earlier on Sunday evening, police fired at least one bean-bag round that was left lying on the street, as they attempted to disperse protesters who had been aiming laser pointers at the station.
Officers had also warned people against hurling bricks at the facility.
A woman was also pepper sprayed after she confronted officers and yelled at at them.
Last updated: 2019-09-23 HKT 00:39