Hong Kong announced a series of strict pandemic control measures Wednesday, including suspending flights from the United States and seven other countries, as it scrambled to contain an incipient coronavirus outbreak.

The new measures came as authorities held thousands of passengers from a cruise ship under mandatory quarantine to trace a COVID-19 case.

The flight bans will deepen the city’s isolation from the outside world and mark a return to the tough restrictions the city imposed in the early days of the pandemic.