A protester was filmed launching himself at a riot officer in Hong Kong.
A video showed a man fly kicking a policeman, who then fell to the floor and was beaten by two other men who unsuccessfully tried to snatch his gun.
At the end of the clip, the officer seemed to be unhurt and got back to his feet.
Violence spiralled as protests stretched from Sunday afternoon into the night, with police struggling to restore order.
Authorities said an officer was attacked from behind with a sharp weapon earlier in the day and was left with a bleeding neck wound.
A beating after dark by a group of masked protesters left a man bleeding profusely.
The guerrilla-like tactics sought to maximize the disruption and visibility of protests at a time when anti-government demonstrations have shown signs of flagging as they stretch into a fifth month.
Pressure from a government ban on the face masks worn by many protesters and extreme violence earlier this month appeared to have whittled down protest numbers.
Masked protesters wielding hammers wrecked a Huawei store that was apparently targeted because of the brand’s links to mainland China.
Another store was broken into and trashed, with protesters spray-painting ‘we are not stealing.’
The words ‘black heart’ were also painted in black inside a vandalized Starbucks, another frequent target of the anti-government and anti-China protests that have gripped the semi-autonomous Chinese territory since June.
The protests concentrated in the international business hub began in response to a now-withdrawn extradition bill that would have allowed criminal suspects to be sent for trial in Communist Party-controlled courts in mainland China.
The movement broadened to encompass universal suffrage, an independent inquiry of the policing methods used against protesters and other demands.