HONG KONG (AP) — One of the world's busiest airports was struggling to reopen the morning after thousands of pro-democracy demonstrators crowded into Hong Kong's main terminal and forced flight cancellations.

Passengers were checking in for flights Tuesday morning in a sign operations were returning to normal, although protesters have shown no sign of letting up on their campaign to force Chief Executive Carrie Lam's administration to respond to their demands.

About 200 flights had been canceled.

Passengers unable to leave on Monday were among those crowding in the departure hall.