Footage of the attack posted on social media showed the marauding masked gang, wearing white T-shirts, attacking crowds on the platform and inside train carriages at Yuen Long MTR station, located in the far northwest of the semi-autonomous Chinese city.
Protesters were reportedly at the mercy of the mob for almost an hour before police arrived and at least 45 people were injured, some seriously.
Hong Kong police confirmed at a news conference on Tuesday that while there have been 28 arrests made stemming from the July 21 violence, none have yet been charged.
On Wednesday evening the Hong Kong government said in a statement that activists had blocked roads outside the station and that after “repeated warnings to the protesters went futile, police are now conducting a dispersal operation, using minimum force.”
Hong Kong has been beset by a major political crisis, with last weekend marking the 11th consecutive weekend of mass demonstrations, first sparked by widespread opposition to a controversial bill that would enable China to extradite fugitives from the city.
While the demonstrations began fairly peacefully in March, clashes between police and demonstrators have marred recent demonstrations with tear gas, alleged police brutality, and angry confrontations at the fore of the protests.
CNN’s AnneClaire Stapleton, Julia Hollingsworth and Tara John contributed to this report.