LOS ANGELES (AFP) -- Passengers on a cruise ship stranded off the coast of San Francisco were confined to their cabins Thursday as tests were conducted to determine if any of the nearly 3,500 guests and crew had contracted the new coronavirus.

Authorities said the Grand Princess, which had been scheduled to dock on Wednesday, would remain at sea until the test results of those who had shown symptoms of the virus are known.

The California National Guard said it had flown test kits to the ship Thursday morning and the results were expected to be released early Friday.

Health officials sounded the alarm after two passengers who had been on board during a previous voyage between San Francisco and Mexico later fell ill and one of them died.

Several other passengers who had remained on the vessel for its next voyage to Hawaii also developed flu-like symptoms during that trip.

Officials said there were 2,383 passengers and 1,100 crew on board the ship.

One of the passengers contacted by AFP said there was no panic on board and people seemed to be taking the setback in stride.

"I can't get over how the news is sensationalizing our ship," said Carolyn Wright, 63, a professional photographer from New Mexico traveling with a friend. "There were two cases on the previous cruise and they act like everybody on board has the plague."

She said passengers had been free to roam about the ship but on Thursday were told to stay in their cabins after lunch.

Wright added that passengers were told by the ship's captain to expect an update on the test results on Friday.

'I'm not really worried'

"I think it's all closing the barn after the horse has left," Wright said via text messages, referring to the decision to confine people to their rooms.

"I'm not really worried. If you look at the odds, our risk is pretty low."

She said the passengers -- most of them between 60 and 90 years old -- were in good spirits "although that may change if we are stuck in our cabins for too long."

"Everyone was calm and content up until now," she said. "But room service isn't answering and people are going to get upset quickly without food or liquor."

Health officials said it was unclear when or where the ship would be allowed to dock.

Various agencies "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, referring to the formal name of the virus.

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

Carroll said once test results are back, the Centers for Disease Control and Prevention 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."

California Governor Gavin Newsom said authorities were trying to contact some of the 2,500 passengers who were on board the previous voyage.

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.

Worldwide, more than 3,000 people have died from the fast-spreading virus that has infected more than 100,000 people in some 85 countries. (AFP)