Riot police clashed with demonstrators at the airport on Tuesday night after angry crowds assaulted and detained two men they believed to be mainland agents.
Thousands of anti-government protesters occupied the airport terminal for a second consecutive day, forcing the cancellation of outbound flights.
The protesters cornered the first man around 9pm, saying he was a mainland security officer, and started punching him. He complained of feeling unwell but the crowd blocked paramedics from taking him away. He appeared to lose consciousness and was given oxygen.
Around 11pm police stormed the building. They appealed to the protesters to stop obstructing them, adding that they were not carrying out a dispersal operation but just wanted to escort the man and ambulance workers to hospital.
Police used pepper spray and batons as they tried to get access to the injured person, Protesters fought back, with one wrestling a baton from an officer and repeatedly beating him with it. The officer, who had fallen onto the floor, responded by pulling his gun and briefly pointing it at the protesters.
During the chaos, the injured man was successfully taken aboard an ambulance, but demonstrators started throwing water bottles and rubbish at police, and used baggage carts to try to block the ambulance from leaving.
Later the protesters assaulted and tied up another mainland man who they said had been taking close up headshots of people with his mobile phone. They asked if he was a reporter but then used cable ties to tie his hands together when he apparently failed to co-operate with them.
Demonstrators are wary about police or others disguising themselves as protesters or reporters after black-clothed "decoy" officers helped arrest people during clashes at the weekend.
Legislators Fernando Cheung and Kwok Ka-ki turned up at the airport in an attempt to mediate. Kwok appealed to the mob, saying: "The whole world is watching, don't mete out extrajudicial punishment."
However, the crowd accused the man of being involved in previous attacks on demonstrators after they found T-shirts saying "I love HK police" in his bag.
Paramedics were finally able to take the man out on a stretcher at around midnight. The editor of the state-run tabloid, Global Times newspaper, said later that he was one of their reporters and had just been covering events.
Last updated: 2019-08-14 HKT 12:05