Donald Trump used a freewheeling press conference on Friday, intended to provide updates on the coronavirus, as an opportunity to attack Democrats, praise his own intelligence, lash out at CNN and spread false and misleading information about the status of the outbreak, as a slew of new cases were confirmed aboard a cruise ship off the California coast.

Speaking at the Centers for Disease Control’s (CDC) main campus in Atlanta, Georgia, while wearing his red “Keep America Great” re-election campaign hat, the president went on a rant criticizing Washington state’s governor, Jay Inslee, as a “snake” and saying he disagreed with his vice-president’s complimentary remarks toward the Democrat. Inslee, who ran for president last year, is overseeing the response to the most serious outbreak in the US.

In a moment that some commentators have called one of the most “disturbing” and “frightening” remarks of Trump’s response to the public health crisis, the president also said he would prefer that cruise ship passengers exposed to the virus be left aboard so that they don’t add to the number of total infections in the US.

“I like the numbers being where they are,” said Trump, who appeared to be explicitly acknowledging his political concerns about the outbreak: “I don’t need to have the numbers double because of one ship that wasn’t our fault.”

The president further implied that the coronavirus test was available to anyone who needed it, even though his own administration has acknowledged that there is currently a shortage among US healthcare providers.

Trump’s remarks came as the vice-president, Mike Pence, announced that 21 people on a cruise ship being held off San Francisco had tested positive for coronavirus. He also urged older Americans to “use caution” in planning any cruise ship vacation.

Speaking at the White House, Pence said the government was planning to bring the Grand Princess cruise ship into a “non-commercial port” where all the passengers and crew would be tested. They would be quarantined and treated as needed.

There are more than 3,500 people on the ship, counting passengers and crew. Pence said 19 of those who tested positive were crew members and two were passengers.

The US death toll from the coronavirus has climbed to 14, according to Johns Hopkins’ tracker, with 329 cases scattered across the country. All but one of the deaths were in Washington state.

Inslee later responded on Twitter to the president’s personal insults and attack, saying: “My single focus is and will continue to be the health and well-being of Washingtonians. It’s important for leaders to speak with one voice. I just wish the president and vice president could get on the same page.”

In California, a military helicopter crew lowered test kits onto the 951ft (290-meter) Grand Princess by rope and later retrieved them for analysis at a lab as the vessel lay at sea off the coast, under orders to keep its distance from shore.

Elsewhere in the US, the University of Washington, which has about 50,000 students, said on Friday that it would cancel in-person classes and conduct courses and exams remotely while the Seattle area deals with a coronavirus epidemic that has put the region at the center of the outbreak in the US.

Donald Trump listens as the CDC director, Dr Robert Redfield, speaks on Friday. Photograph: Jim Watson/AFP via Getty Images

In an email to staff the university’s president, Ana Mari Cauce, said campuses would remain open for other services, such as medical services, dining, residence halls, and recreation and athletics events.

But in the absence of students, crews of workers would deep-clean classrooms, libraries and other public spaces. “Our goal is to make sure that students’ academic work is fairly recognized and that any disruption does not present a disadvantage to their future academic progress,” Cauce said.

Seattle University, which has about 7,300 students, and Seattle Pacific University, which has about 3,500 students, also announced Friday that they would not be holding in-person classes through the end of winter quarter, 20 March. Both schools said they were not aware of any confirmed cases of coronavirus on their campuses.

At the center of the Seattle-area outbreak was a suburban nursing home, now under federal investigation. Families of nursing home residents voiced anger, having received conflicting information about the condition of their loved ones.

One woman was told her mother had died, then got a call from a staffer who said her mother was doing well, only to find out she had, in fact, died, said Kevin Connolly, whose father-in-law is also a facility resident.

“This is the level of incompetence we’re dealing with,” Connolly said in front of the Life Care Center in Kirkland.

The coronavirus has infected about 100,000 people worldwide 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.

Donald Trump signed an $8.3bn measure to help tackle the outbreak. It provides federal public health agencies with money for tests and for potential vaccines and treatments and helps state and local governments prepare for the threat and respond to it.

Some major businesses in the Seattle area, where researchers say the virus may have circulated undetected for weeks, have shut down some operations or urged employees to work from home. That includes Microsoft and Amazon, the two tech giants that together employ more than 100,000 people in the region.

King county is buying a motel for $4m to house patients and hopes to have the first of them in place within days at the 84-room Econo Lodge in Kent, about 20 miles (32 km) from Seattle. The rooms’ doors open to the outside rather than to a central hallway, reducing the likelihood of contact between patients.

The plan was met with resistance from local leaders, including Kent’s police chief, Rafael Padilla, who called it “ill-advised and dangerous” and warned: “At any point a patient can simply walk into our community and spread the virus.”

New York’s mayor implored the federal government to send more test kits to his state. Gap closed its New York office and asked employees to work from home until further notice after learning that an employee had the virus.