Demonstrators recently adopted a flash-mob strategy, retreating when pressed by police only to re-emerge at another location. Others hurled taunts and rocks, and shone laser pointers at officers' faces until squads of riot police pushed forward, dousing the crowd with tear gas.
The fresh demonstrations came after the city's leader Carrie Lam pledged she would not grant concessions to the protesters as their movement enters its third month.
Demonstrators gathered in two districts on Sunday.
After mention of the protests was initially censored - as with most unrest in China - photos and videos of violence have become a more common sight in mainland Chinese media, which has emphasized the radical elements of the anti-government movement and sought to paint it as controlled by the United States and other foreign "black hands". She said she was anxious about escalating violence, but added that "the protesters were just trying to protect themselves against police violence".
"History will prove what we did to be right".
Pro-democracy activists staged three days of sit-ins at the airport from Friday, but the protests were significantly smaller than Monday's which followed a weekend of often violent confrontations between police and demonstrators across the city.
Hong Kong's Airport Authority has cancelled all flights not yet checked in by Monday afternoon as anti-government protesters peacefully demonstrated at the airport for a fourth day.
Seeking to clear streets quicker than before, police fired tear gas and charged with batons at flashpoints downtown and in working class districts on Sunday.
Elsewhere, two petrol bombs were thrown at police and at least one officer suffered burns.
A number of people, including a police officer, were injured in the clashes.
One image widely shared on social media showed a woman, who was reportedly shot by a police projectile, bleeding heavily from her eye.
Tear gas was also used against protesters in several places in Kowloon. "According to the safety guidelines of the supplier, tear gas can only be used outdoors or in a well-ventilated area".
A massive traffic jam soon formed on the highway leading back to Hong Kong's city centre.
'There will still be citizens going out on the streets to protest, but we can not control them and we do not have the authority to control them, ' Yu said.
Scantlebury and her brother, Julian, grew up in Hong Kong but study in the United Kingdom and Australia, respectively.
In the early hours on August 11, the Hong Kong government released a press release saying that it had arrested 16 people overnight for "unlawful assembly, possession of offensive weapon, assaulting a police officer, and obstructing a police officer in the execution of duties".
"Hong Kong's radical demonstrators have repeatedly used extremely risky tools to attack police officers, which already constitutes a serious violent crime, and also shows the first signs of terrorism emerging", Yang Guang, a spokesman for the Hong Kong and Macau Affairs Office (HKMAO), said at a press briefing.