The Grand Princess cruise ship that has been stranded off the California coast for four days after it was halted due to a coronavirus outbreak will dock at the Port of Oakland, the ship’s captain announced Saturday night to the 3,500 passengers and crew members on board.

The captain told passengers they would dock Sunday afternoon, but Princess Cruises later said that plan was pushed to Monday because the U.S. Centers for Disease Control and Prevention needs more time to modify procedures for getting people off the ship.

The captain’s news was delivered not long after Gov. Gavin Newsom held a conference call with city officials in Oakland to inform them of the plans.

Passengers will disembark over several days, with seriously ill patients evacuated first and moved to hospitals for treatment, the captain said in his announcement. Twenty-one people on board the ship have tested positive for coronavirus, but not all of them have symptoms, cruise officials have said.

California residents on the ship will be taken to federally operated quarantine facilities in the state and will be tested for the virus there, the captain said. U.S. residents from other states will be moved out of California. It was not yet known where the international passengers and crew members would go. Crew members will remain quarantined on the ship after it docks, Princess Cruises said.

The ship will dock at the Ports America site, which has been empty for several years, said Oakland City Councilman Larry Reid, who was not on the call with the governor but was informed of the docking plans Saturday night.

Earlier Saturday, as the cruise ship passengers awaited word of their final destinations, the coronavirus outbreak in California climbed past 100 cases, with six new patients diagnosed in San Francisco and eight in Santa Clara County. More than 60 people in the Bay Area have tested positive for the coronavirus, including a faculty member at Stanford and an employee of the FBI.

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On the Grand Princess, which is being held 50 miles off the California coast, 19 crew members and two passengers have tested positive for the virus.

The ship was due in the Port of San Francisco on Saturday but was held at sea after a passenger from a previous trip — a 71-year-old Placer County man — tested positive for coronavirus and died. The ship has been circling offshore since Wednesday night, when state and federal public health officials ordered it to halt its voyage home.

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“We need to get the ship into a port as soon as possible,” said Jan Swartz, group president of Princess Cruises and Carnival Australia, in a news conference Saturday afternoon.

Dr. Grant Tarling, chief medical officer for Carnival Corporation, said he believes that the source of the cruise ship outbreak was the Placer County resident, who appears to have been infected before boarding the Grand Princess Feb. 11. That passenger was on a cruise to Mexico that returned to San Francisco on Feb. 21.

The man sought medical care on the ship for respiratory problems Feb. 20 and reported that he had been unwell for six or seven days, Tarling said. That means he first was symptomatic just two or three days after boarding the ship. People usually show symptoms of coronavirus infection four to five days after they are infected.

“So we believe his illness was probably community acquired somewhere in California, before he joined the ship,” Tarling said.

If that’s the case, then the coronavirus has been circulating in California longer than earlier reports suggested. The first reported case of community infection was Feb. 26, in a Solano County resident, but the Placer County man would have been infected at least two weeks earlier.

A waiter who served at the man’s dining table during the Mexico trip, and then stayed on board the Grand Princess for the Hawaii cruise — which is the trip that is currently stalled at sea — was one of the 21 people to have tested positive on Friday. Most of the 19 crew members who tested positive were on both the Mexico and the Hawaii trips, Tarling said. But the two passengers who have tested positive were not on the Mexico cruise.

About nine California residents — including people in Sonoma, Contra Costa and Alameda counties — who were passengers on the February trip to Mexico have now tested positive.

All of the 2,400 passengers currently on the Grand Princess have been quarantined to their rooms, cruise officials said. Meals are delivered to them three or four times a day by masked crew members. The people who tested positive are being held in isolation, Tarling said.

Vice President Mike Pence has said that everyone on board will be tested for the virus, but cruise line officials said they had not heard when that would happen.

A critically ill passenger and her husband were evacuated by a Coast Guard vessel early Saturday. The sick individual, a woman in her 70s, was taken to a hospital for treatment unrelated to coronavirus, the cruise line said.

The six cases reported by San Francisco on Saturday are not related to the cruise ship, a public health spokeswoman said. All of the people who were newly diagnosed are isolating at home and in good condition. The San Francisco residents who earlier tested positive were both hospitalized.

On Saturday, San Francisco banned all non-essential group activities in city-owned facilities for two weeks in an effort to contain the rapid spread of the virus.

The ban applies to gatherings of more than 50 people for social, cultural or entertainment purposes. The order by the Department of Public Health will be effective until March 20.

Staff writers Lauren Hernandez, Lizzie Johnson and Steve Rubenstein contributed to this report.

Erin Allday is a San Francisco Chronicle staff writer. Email: eallday@sfchronicle.com