Hong Kong police on Saturday slammed anti-government protesters for besieging their headquarters, calling the demonstration "illegal and irrational" as they vowed to pursue the ringleaders.
"Police have shown the greatest tolerance of protesters who assembled outside PHQ (police headquarters) but their means of expressing views has become illegal, irrational and unreasonable," the city's police said in a statement.
"Police will stringently follow up on these illegal activities."
Thousands of protesters blockaded the police headquarters throughout Friday and into the small hours of Saturday morning, the latest manifestation of angry demonstrations sweeping the city.
The international finance hub has been rocked by the worst political unrest since its 1997 handover to China.
Millions have marched this month to oppose a proposed law that would have allowed extraditions to the Chinese mainland.
Officers had used tear gas and rubber bullets last week to clear protesters during a massive demonstration outside the city's parliament, sparking widespread anger against the police force.
The spark for the current wave of protests was the extradition bill, which the city's pro-Beijing leader Carrie Lam has postponed in the face of the huge public backlash.
But the demonstrations have since morphed into a wider movement against Lam's administration and party leaders in Beijing after years of sliding political freedoms.
Police have also become a focus of protester anger.
During Friday's demonstrations outside their headquarters, large crowds of protesters blockaded entrances, taped over CCTV cameras and shouted at police.
Many chanted "release the righteous" and "shame on police thugs" -- references to those detained during violence last week between demonstrators and the police.
Officers remained inside their fortified building throughout.
The protest was noisy but peaceful -- with the exception of some thrown eggs and demonstrators shining laser pens at the windows. The crowds eventually dispersed around 4:00 am (2000 GMT Friday).
Police said some 60 emergency calls could not be "immediately handled" because of the blockade and that 13 members of staff were "sent to hospital for treatment".
The statement did not say how the staff were injured.
Opposition groups have demanded an investigation into allegations of police brutality and the release of those detained during the clashes, in addition to Lam's ouster and the permanent cancellation of the extradition bill.
Rights group Amnesty International said Friday it had verified multiple instances of police violence that breached international laws while the Hong Kong Bar Association added its voice to calls for an investigation into police tactics.
Police have defended using tear gas and rubber bullets on 12 June as a necessary and proportionate response to meet violent protesters who were trying to break into the city's parliament.