Hong Kong International Airport cancelled all departures on Monday, as thousands of anti-government protesters occupied and caused disruption.
Passengers have been told not to travel to the airport, which is one of the world’s busiest transport hubs.
In a statement, officials blamed “seriously disrupted” operations.
Many of those protesting are critical of the actions of police, who on Sunday were filmed firing tear gas and non-lethal ammunition at close range.
Some protesters wore bandages over their eyes in response to images of a woman bleeding heavily from her eye on Sunday, having reportedly been shot by a police projectile.
In a statement on Monday afternoon, Hong Kong’s Airport Authority said they were cancelling all flights that were not yet checked in.
More than 160 flights scheduled to leave after 18:00 local time (10:00 GMT) will now not depart.
Officials said arrivals already heading into Hong Kong would still be allowed to land, but other scheduled flights have been cancelled.
As rumours spread that police plan to move in on protesters on Monday evening, thousands have opted to leave on foot. There are large backlogs for transport back into the centre, local reports say.
The BBC’s Stephen McDonell, who is at the scene, says the airport has effectively shut down while authorities work out how to deal with the crisis.
Hong Kong’s mass demonstrations and unrest show no sign of abating, more than two months after they were sparked by a controversial extradition bill.
Beijing officials have strongly condemned Sunday’s violence and linked violent protesters to “terrorism”.