A Marin County man has tested positive for the coronavirus, health officials said Monday.

The man was among the 56 passengers from Marin who were exposed to the virus on the Grand Princess cruise ship last month.

It is the first confirmed case of COVID-19, the illness caused by the novel coronavirus, in a county resident. Health officials declined to release details about the man’s identity, but said he is “elderly.” He is being treated for the illness at a hospital in the county.

A video from your Public Health Officer on #COVID19 #Coronavirus Latest news release regarding first Marin County COVID-19 case: https://t.co/ywXRagNEx8 pic.twitter.com/6KdtUBMHbg — Marin County (@maringov) March 9, 2020

“We have identified everyone who was in close contact with this individual over the past two weeks to ensure that they are isolating themselves at home and being tested so that we can contain any further spread,” said Dr. Matt Willis, the county’s public health officer, in a video announcing the diagnosis Monday.

The man was among the seven cruise passengers who were tested for the virus late last week because they had symptoms of the illness or were in close contact with a symptomatic person, according to the county Department of Health and Human Services. Many of them are still awaiting test results, officials said.

The cruise passengers, who got off the ship in San Francisco on Feb. 21 after an 11-day voyage to Mexico, were unaware they had been exposed to the coronavirus until Wednesday, when Princess Cruises contacted its customers to warn them that the illness had been spreading on the ship, according to county health officials. They had not been quarantined.

Health officials made contact with each of the Marin passengers last week to find out if any were symptomatic. Those who were deemed at risk of being infected were tested and asked to stay at home in isolation. Two were hospitalized due to severe respiratory illness.

At least five other people who had been on the ship, including Sonoma, Contra Costa and Placer County residents, have tested positive for the disease. A 71-year-man who had been on cruise died of the illness last week after returning home to Placer County.

After its voyage to Mexico that ended Feb. 21, the Grand Princess left San Francisco for another cruise. The ship made it to Hawaii, but its final stop in Ensenada, Mexico, was canceled after the Placer County man who had been on the previous cruise died.

The ship docked at the Port of Oakland on Monday after idling off the California coast for several days while health providers tested passengers for the coronavirus. The testing confirmed that 21 of the roughly 3,500 people on board have been sickened. The health department said it doesn’t know whether any of the passengers are Marin residents.

A woman who was sickened by the virus after a cruise in Japan was transferred to Kaiser Permanente hospital in San Rafael from Travis Air Force Base in Solano County. She was the first person treated for the virus in Marin, but she was not a county resident. The health department said Monday she had been released from the hospital, where she had been quarantined for more than a week.

Willis has said that health officials “expect to see” community spread of the virus in Marin.

The health department announced Monday afternoon it is recommending that “nonessential” indoor gatherings with more than 100 people be canceled or postponed “out of an abundance of caution.”