At least one Hong Kong police officer fired a warning shot during clashes with protesters armed with sticks on Sunday, the first time a live round has been used in three months of protests.

The incident occurred as riot police also deployed water cannon trucks for the first time since mass demonstrations began, shooting volleys of tear gas and rubber bullets at protesters chucking bricks and homemade petrol bombs, shrouding the mostly residential neighbourhood of Tsuen Wan in chaos.

Several officers, not equipped with riot gear, drew their pistols after a group of protesters attacked a police van, forcing those inside to exit the vehicle.

At least one officer fired his weapon after another fell to the ground as protesters charged. Earlier, protesters scattered after water cannon and tear gas were deployed, some taking shelter in a nearby mall and barricading themselves in, while others headed for neighbourhoods several miles away, sparking off more clashes through the night.