Hong Kong International Airport saw chaotic scenes on a second consecutive day of massive anti-government protests that have paralysed one of Asia's key transport hubs.
Squads of riot police arrived shortly before midnight after thousands of demonstrators again flooded the terminal buildings during the day.
Flight departures were brought to a standstill amid scuffles.
At least three men were mobbed inside the airport by protesters.
They were said to be holding identity cards showing they were police officers from mainland China.
Hong Kong police have admitted deploying officers disguised as anti-government protesters during the unrest in the city.