Hong Kong police fired water cannon on anti-government protesters in an unprecedented move on Sunday, after an initially peaceful march through a residential district in the western Kowloon peninsula took a violent turn.
The two cannon vehicles were used on Sunday to clear barricades and disperse crowds in the Tsuen Wan district.
As tensions escalated, black-clad protesters threw projectiles, including bricks and petrol bombs.
During one clash, police pointed their guns at protesters. Reports said one officer fired a warning shot.
The police officer fired a gun into the air at around 8pm local time after he was surrounded by eight to 10 protesters, according to a district council protest monitor.
It was the first time that both the water cannon and a purported gunshot had been aimed at protesters in the 12 weeks of anti-government demonstrations.
The clashes were some of the most intense yet in Hong Kong since protests began on June 9 against a legislative bill that would have allowed for criminal extradition to mainland China, which has a separate legal system from Hong Kong.
Images on social media show the water-cannon vehicles being driven through the streets of Tsuen Wan, where a group of demonstrators had set up roadblocks and dug up bricks from the pavement.
The vehicles are equipped with surveillance cameras and multiple water-cannon nozzles, and police had said they would only be used in the event of a “large-scale public disturbance”.
As demonstrations enter their 12th week, protesters said they are still as determined as ever to protest against the government as they see themselves taking a last stand against political repression from China.
There was another, more peaceful rally on Sunday comprised of a few hundred people, some of them family members of the police, who called for a political solution to the crisis.
Hong Kong is a former British colony that returned to Chinese rule in 1997, and its unique identity and semi-autonomous status remain important rallying points for protesters.
Many believe the city has seen a decline in civil and political rights since the failure of the 2014 democracy protests known as the Umbrella Movement.