More than 6,000 people were still on board an Italian cruise ship after the liner was placed on lockdown over fears two Chinese passengers could be carrying the coronavirus.

The Costa Smeralda is currently being held near Civitavecchia, 35 miles north of Rome after a 54-year-old woman from Macao—an autonomous region on the south coast of China—came down with a fever and breathing problems, according to ABC7 Chicago.

The woman was put into isolation overnight in a hospital ward on the ship. Her husband, who has no symptoms, was also quarantined and they have been tested for the coronavirus.

“All the planned mechanisms were activated,” Italian Coast Guard Cmdr. Vincenzo Leone said at the port of Civitavecchia. “Health authorities are on board, doing checks. The situation is under control. There’s a security cordon on the dock.”

Preliminary tests on the pair suggested they were not carrying the virus, but officials said that they must wait longer for more accurate results, according to The Guardian.

At that time, there were roughly 6,000 passengers and 1,000 crew members on the ship.

Later Thursday, Jan. 30, just over 1,000 passengers were allowed off the ship for a walk through sunny Rome.

The ship was sailing from Mallorca, Spain, to Civitavecchia on a weeklong Mediterranean cruise.