Clashes have broken out at Hong Kong International Airport between police and protesters. Police were forced out of the airport as protesters threw objects at them.
Riot police have clashed with pro-democracy protesters at Hong Kong's airport, moving into the terminal where the demonstrators had shut down operations at the busy transport hub for two straight days.
Officers armed with pepper spray and swinging batons confronted the protesters who used luggage carts to barricade entrances to the airport terminal.
Police took several people into a police van waiting at the entrance to the airport's arrivals hall.
Police said they tried to help ambulance officers reach an injured man whom protesters had detained on suspicion of being an undercover agent.
Protesters also detained a second man who they suspected of being an undercover agent.
After emptying out his belongings, they found a blue T-shirt that has been worn by pro-Beijing supporters that they said was evidence he was a spy.
Earlier in the day, authorities were forced to cancel all remaining flights as the city's pro-Beijing leader warned that the protesters had pushed events onto a "path of no return".
After a brief period early in the day when flights were able to take off and land, the airport authority suspended check-in services for departing flights as of 4:30pm.
Departing flights that had completed the process would continue to operate.
It said it did not expect arriving flights to be affected, although dozens were already cancelled.
The authority advised people not to come to the airport, one of the world's busiest transport hubs.
More than 200 flights were cancelled on Monday and the airport was effectively shut down with no flights taking off or landing.
Passengers have been forced to stay in the city while airlines struggle to find other ways to get them to their destinations.