Tensions between police and protesters flared on Tuesday at Hong Kong International Airport, after the second consecutive day of protests forced the airport authority to ground all departing flights.

Thousands of protesters swarmed the terminals, disrupting operations at one of the world’s most important transportation hubs. Frustrated travelers confronted protesters blocking their way through the airport, leading to arguments and scuffles, at least one of which led to a physical altercation.

There are reports of clashes, pepper spray and protesters being arrested.

In a statement issued late Tuesday, the authority advised all passengers to leave the terminals, saying that operations have been “seriously disrupted.”

Here’s what travelers to and from Hong Kong need to know.

What’s happening in Hong Kong?

Sparked by proposed legislation that would have changed extradition policies between Hong Kong and other places, including mainland China, antigovernment protests in Hong Kong are currently in their third month. Previous protests have occurred mainly downtown, in popular shopping areas and near government buildings.