Thousands of passengers stranded aboard a cruise ship stricken by coronavirus have been told they can expect to finally dock in the port of Oakland, California, on Monday, as authorities ordered its sister ship to wait off the coast of Florida until two crew members were tested.

The Grand Princess has been circling off California for four days having been refused permission to land in San Francisco amid evidence that the vessel was the breeding ground for a cluster of more than 20 cases that resulted in at least one death.

Its captain, John Smith, told the 3,500 passengers from 54 countries that Princess Cruises, the ship’s owners, had arranged for it to dock tomorrow.

“An agreement has been reached to bring our ship into the port of Oakland,” he said in a loudspeaker announcement late Saturday recorded by passengers. “After docking, we will then begin a disembarkation process specified by federal authorities that will take several days.”

That process was expected to include passengers being taken into quarantine and crew members staying aboard.

Meanwhile in Florida, the Regal Princess was refused permission to dock in Fort Lauderdale on Sunday morning pending results of tests on two crew members who transferred recently from the Grand Princess.

Princess Cruises did not respond immediately to questions about how many passengers were on board or what measures were being taken as the ship stayed at sea between Fort Lauderdale and Miami, but travelers aboard posted social media pictures of what appeared to be a US Coast Guard cutter taking virus testing kits ashore.

“The Coast Guard transmitted a no-sail order and information order issued by Health and Human Services and Centers for Disease Control and Prevention (CDC),” a spokesperson told the Guardian in a written statement that did not confirm the ship’s identity.

“This morning a Coast Guard Miami small boat crew, in support of that order, transported test kits to a vessel offshore southern Florida. We will assist health officials to ensure the safety and health of all passengers and crew aboard, and will continue to collaborate with our interagency and industry partners as the whole of US government responds and mitigates risk of coronavirus.”

The Miami Herald reported that the ship, which has a capacity of 3,500 passengers and 1,300 crew, was returning to Port Everglades from a 14-day Caribbean cruise but was ordered to stay at sea.

The newspaper said passengers were awakened by a 5.30am announcement on Sunday informing them that the ship was being held while federal health authorities tested two crew members who joined from the Grand Princess at the beginning of the voyage.

It reported that the crew members being tested had not shown symptoms of the virus that infected 21 people aboard the Grand Princess, 19 of them crew, and that the testing was expected to be completed within a few hours.

A cruise by the Regal Princess scheduled to depart Port Everglades on Sunday was already canceled.

The US death toll from the virus rose to 21 on Sunday, with most victims in Washington state. The number of infections, meanwhile, swelled to more than 550, scattered across 30 states, with Kate Brown, the governor of Oregon, the latest to declare a state of emergency on Sunday afternoon after 14 cases were confirmed there.

Passengers aboard the Grand Princess holed up in their rooms awaiting news, with crew members wearing masks and gloves delivering food in covered plates on trays left outside cabin doors.

Grant Tarling, chief medical officer for Carnival Corporation, said it is believed a 71-year-old Northern California man who later died of the virus was probably sick when he boarded the ship for a 11 February cruise to Mexico.

The passenger visited the medical center the day before disembarking with symptoms of respiratory illness, he said. Others in several states and Canada who were on that voyage also have tested positive.

The passenger likely infected his dining room server, who also tested positive for the virus, Tarling said, as did two people traveling with the man. Two passengers now on the ship who have the virus were not on the previous cruise, he said.

Some passengers who had been on the Mexico trip stayed aboard for the current voyage – increasing crew members’ exposure to the virus.

Donald Trump, the US president, was playing golf near his Mar-a-Lago retreat in Florida on Sunday as the crisis continued to escalate. Earlier in the week he said he would prefer not to allow the passengers on to American soil but would defer to experts.

“I don’t need to have the numbers [of US cases] double because of one ship that wasn’t our fault,” Trump said Friday while touring CDC headquarters in Atlanta. “And it wasn’t the fault of the people on the ship either. And they are mostly American, so I can live either way with it.”

Another Princess ship, the Diamond Princess, was quarantined for two weeks in Yokohama, Japan, last month because of the virus. Ultimately, about 700 of the 3,700 people aboard became infected in what experts pronounced a public-health failure.

Hundreds of Americans aboard that ship were flown to military bases in California and other states for two-week quarantines. Some later were hospitalized with symptoms.

An epidemiologist who studies the spread of virus particles said the recirculated air from a cruise ship’s ventilation system, plus the close quarters and communal settings, make passengers and crew vulnerable to infectious diseases.

“They’re not designed as quarantine facilities, to put it mildly,” said Don Milton of the University of Maryland.

Worldwide, the virus has infected more than 100,000 people and killed more than 3,400, the vast majority of them in China. Most cases have been mild, and more than half of those infected have recovered.