What happened was in late afternoon, police fired tear gas and water cannons laced with some sort of blue dye at protesters who had gathered outside government buildings.
Police said officers also fired two warning shots into the air after being attacked by a group of "violent protesters who attempted to once snatch police pistols". In-town check-in services at Airport Express stations were also halted.
The financial hub has been thrown into chaos by a largely leaderless movement that has drawn millions onto the streets to protest against what they see as an erosion of freedoms and increasing interference in their affairs by Beijing.
Late at night, a video from Hong Kong broadcaster TVB showed police on the platform of Prince Edward subway station swinging batons at passengers who backed into one end of a train vehicle behind umbrellas.
Earlier on Saturday, protesters throwing petrol bombs and setting fires had been quickly met with tear gas, rubber bullets and a water cannon - a suggestion that Hong Kong police's patience is waning after a long summer of conflict.
The MTR subway station in Tung Chung was closed and demonstrators smashed CCTV cameras and lamps with metal poles and dismantled station turnstiles.
Police on Friday confirmed three lawmakers and a district councilor had been arrested over their alleged actions in previous protests, but denied the sweep was timed specifically to weaken the weekend's protests. "The police operation on Saturday only underscores the urgent need for an independent and proper investigation into the policing of the protests". It then warned protesters to take notice that the Asian holiday the Mid-Autumn Festival-which falls on the full moon on September 13 this year-is just days away.
Tens of thousands of protesters took to the streets in the afternoon on August 31, defying a police ban. A dozen blue-uniformed police officers in riot helmets formed a line across an entrance corridor to keep them out of the terminal.
China's state news agency Xinhua posted a video on Twitter late Saturday of armed Chinese riot police holding "anti-riot drills in Shenzhen", a city which borders Hong Kong.
Beijing had decided five years ago they were going to maintain control over how Hong Kong elects its direct leader, and that set off something called the Umbrella Movement, which is a pro-democracy protest that has partly inspired the current protests. To tell us more, we're joined now by NPR's Emily Feng, who's in Hong Kong.
On Saturday, protesters took to the streets after police refused permission for a march to mark the fifth anniversary of a decision by China against fully democratic elections in Hong Kong.
Flights had so far not been disrupted, while riot police are present inside the terminals.
Hong Kong media say another group of protesters is gathering in the Tsim Sha Tsui district on the other side of Hong Kong's harbor.
"All we can do now is come out and support [the movement]", she said.
Police had banned the demonstration on security grounds and arrested several key activists and legislators in a dragnet on pro-democracy figures.
The former British colony has been governed under the "one country, two systems" arrangement since its return to Chinese rule in 1997.