US health officials conducted tests aboard a cruise ship off the coast of San Francisco Thursday to determine if any of its nearly 3,500 passengers and crew have contracted the new coronavirus.

Some of the stranded passengers on board the Grand Princess who have shown flu-like symptoms were being tested after one 71-year-old man who had been on board the ship on a previous voyage died from the virus.

The ship had been due to dock in San Francisco on Wednesday but was prevented from doing so.

Officials said there were 2,383 passengers and 1,100 crew on the ship, which cut short its voyage back from Hawaii after passengers and crew members developed symptoms.

“At this time, the Centers for Disease Control and Prevention (CDC), the California State Health Department and the governor’s Office of Emergency Services, with the US Coast Guard are working to determine if COVID-19 is present on the ship,” Mary Ellen Carroll, the head of the San Francisco Department of Emergency Management, told reporters.

She said 35 people had shown flu-like symptoms during the 15-day cruise, with many having already recovered.

“Testing protocols are being put into place on the ship for those passengers and crew that have shown flu-like symptoms or may have been exposed to the virus, and that is happening today,” she added.

Carroll said once test results are back, the CDC and California state officials will determine the most appropriate location for the ship to berth.

“The location needs to provide for the safety of the surrounding community, as well as the passengers and crew,” she said. “The CDC and the state are considering a number of locations including San Francisco.”

On Wednesday, California Governor Gavin Newsom said 11 passengers and 10 crew members were potentially infected with the virus that emerged in China late last year and has spread worldwide, killing more than 3,000 people.

Some 62 guests who remained on board from the ship’s earlier Mexico voyage were being restricted to their cabins for testing, the Princess Cruises company said in a statement to AFP on Wednesday.

“In an abundance of caution, these guests and other potential close crew contacts have been asked to remain in their staterooms until screened by our onboard medical team,” it said.

The Grand Princess belongs to Princess Cruises, the same company which operated the Diamond Princess—the coronavirus-stricken ship held off Japan last month from which more than 700 people tested positive and six died.