All flights in and out of Hong Kong were cancelled on Monday after thousands of pro-democracy protesters flooded the city's airport to denounce police violence.
Violent protests gripped the city during the weekend as demonstrators threw up barricades across the city and police shot tear gas into crowded underground train stations for the first time.
Scores of protesters were arrested on Sunday, with many taken away beaten with batons and bloodied. Tear gas was fired at crowds in districts on Hong Kong island, Kowloon and the New Territories.
Authorities called the demonstrations illegal and dangerous, claiming that protests, which entered their 10th week, have hurt the already-faltering economy and residents' daily lives.
The abrupt shutdown at one of the world's busiest airports came as the Chinese government signalled its rising anger at the protesters, denouncing some of the violent demonstrations as "terrorism".
The developments marked yet another dramatic escalation in a 10-week crisis that had already become the biggest challenge to Chinese rule of Hong Kong since the 1997 British handover.
The protests began to oppose a bill, which could have allowed extradition of Hong Kong residents to the mainland, but soon widened to highlight other grievances, drawing broader support.
Police have arrested more than 600 people since the unrest began more than two months ago.