By Agence France-Presse

Chaos gripped Hong Kong’s airport for a second day Tuesday as pro-democracy protesters staged a disruptive sit-in that paralysed hundreds of flights, saw police fire pepper spray, and a mainland journalist beaten.

Demonstrators defied warnings from the city’s leader, who said they were heading down a “path of no return”, and US President Donald Trump called for calm, saying his intelligence had confirmed Chinese troop movements toward the Hong Kong border.

The latest protest led to ugly scenes at one of the world’s busiest airports, where small groups of hardcore demonstrators turned on two men they accused of being spies or undercover police — and as desperate travellers pleaded in vain to be allowed onto flights.

Hong Kong’s 10-week political crisis, which has seen millions of people take to the streets calling for a halt to sliding freedoms, was already the biggest challenge to Chinese rule of the semi-autonomous city since its 1997 handover from Britain.

But two days of protests at the airport have again raised the stakes for the financial hub.

Beijing is sending increasingly ominous signals that the unrest must end, with state-run media showing videos of security forces gathering across the border.

All check-ins were cancelled on Tuesday afternoon after thousands of protesters wearing their signature black T-shirts made barricades using luggage trolleys to prevent passengers from passing through security gates.

Scuffles broke out between protesters and travellers, and vigilantism occurred when demonstrators turned on two men.

– Mob justice –

Police have recently disguised themselves as activists to make arrests, a move which has sent paranoia soaring among protesters.

The first man was held for about two hours before eventually being led away in an ambulance. Riot police briefly deployed pepper spray and batons to beat back protesters while they escorted the vehicle away from the departures hall.

Another man, wearing a yellow journalist vest, was surrounded, zip-tied and then beaten by a small group who accused him of being a spy.

In a tweet, Hu Xijun, the editor of China’s state-controlled Global Times tabloid — which has vociferously condemned the protests — confirmed the man was a journalist working for the paper.

The man was later driven away in an ambulance after protesters and volunteer medics carried him off.

By early Wednesday, most protesters had left and the South China Morning Post reported that the Airport Authority had obtained an injunction to remove demonstrators, although it was unclear how it would be enforced.

‘Into an abyss’

On Tuesday morning, the city’s leader, Carrie Lam, gave an at-times emotional press conference in which she warned of dangerous consequences if escalating violence was not curbed.

Lam faced fierce questioning from local reporters and at one point appeared to be on the verge of tears.

“Take a minute to think, look at our city, our home, do you all really want to see it pushed into an abyss?” Lam said, although she again refused to make any concessions to the protesters.

Hong Kong’s Hang Seng Index fell 2.1 percent in its third straight day of losses as China’s official Xinhua news agency said the economic “damage has begun to show” from weeks of protest.

The airport became a target on Monday and Tuesday after especially fierce clashes between police and protesters over the weekend in which a woman suffered a severe injury to her right eye. Protesters blamed the injury on a police bean-bag round.

Some travellers voiced sympathy with the demonstrators.

“I understand the basics of the protest and they’ve got a point: it’s about freedom and democracy and it’s incredibly important,” said Pete Knox, a 65-year-old Briton on his way to Vietnam.

Others were conflicted.

Chun-sun Chan, 46, trying to fly home to his two children in Britain, said he felt for the protesters “but I can’t quite reconcile with myself whether this is the right way of doing it”.

‘Mobsters’

The protests began in opposition to a bill that would have allowed extraditions to the mainland, but quickly evolved into a broader battle.

Authorities in Beijing on Monday slammed violent protesters who threw petrol bombs at police officers, linking them to “terrorism”.

On Tuesday, state media upped the ante, calling protesters “mobsters”, warning they must never be appeased and raising the spectre of mainland security forces intervening.

Videos promoted by state media showed Chinese military and armoured vehicles appearing to gather in the southern city of Shenzhen, which borders Hong Kong.

“Our Intelligence has informed us that the Chinese Government is moving troops to the Border with Hong Kong. Everyone should be calm and safe!” US President Donald Trump said in a tweet on Tuesday.

Earlier, speaking to reporters in New Jersey, Trump said he hoped no one would be killed in the protests.

WATCH: