A man in his 50s with an underlying health condition became the first person in the United States to die of coronavirus infection. President Trump announced new travel restrictions Saturday, and health officials scrambled to increase testing nationwide even as they tried to tamp down public fears.

Along with the fatality in Washington state, health officials in the Seattle area confirmed two additional cases of the covid-19 disease and a possible outbreak at a long-term nursing facility — raising alarm because the elderly and sick are among those most vulnerable to the virus. Officials in California’s Santa Clara County announced another case Saturday, and Illinois announced another case Saturday evening.

The new cases bring the number of people apparently infected by community spread of the disease to nine. They have no travel history to regions hit by the virus or encounters with people known to have the disease.

One of the three new cases of infection is a health-care worker at the Life Care nursing home in Kirkland, Wash. Another is a woman in her 70s from the nursing home, now in serious condition, said Jeffrey Duchin, health officer for Seattle and King County. The man who died was not associated with the nursing home.

The nursing home housed 108 residents and 180 workers, and 27 residents and 25 staffers are showing symptoms associated with the novel coronavirus.

“We would not be surprised to find additional cases,” Duchin said.

Life Care Center is tucked away in a residential area. On Saturday afternoon, there were signs at the door that said, “We are having a respiratory outbreak. Notice: no visitors allowed.”

Saturday afternoon, an American Medical Response vehicle arrived at the Life Care Center and two people who appeared to be paramedics put on gowns and masks before entering the facility with a gurney and then brought out a patient from the facility.

As news of the first fatality broke, President Trump announced he would extend an existing travel ban on Iran to apply to any foreign nationals who had been in that country over the past 14 days. He also raised the warning level for travel to Italy and South Korea, recommending Americans not travel to certain regions of those countries with outbreaks of the virus. Trump said he is also considering restrictions across the southern U.S. border. Mexico’s Foreign Ministry later pointed out the country has fewer cases of coronavirus infection than the United States.

At the hastily convened news conference, Trump described the patient who died as a “wonderful woman” in her late 50s. The Centers for Disease Control and Prevention later issued a statement saying it had mistakenly described the patient’s gender in a briefing to Trump and Vice President Pence, and local health officials clarified the deceased patient was a man.

Trump praised his administration’s response to the virus, calling his earlier decision to ban foreign nationals from China “a lifesaver,” and he urged people to remain calm and to go on living their lives normally.

“Healthy people, if you’re healthy, you will probably go through a process and you’ll be fine,” Trump said.

Saturday’s fatality and new cases, however, were the clearest sign to date that delays in testing may be masking the virus’s widespread presence in the United States. Because of problems with test kits the CDC sent to state labs and strict limits on who could be tested, Washington state health officials didn’t test until the past few days the man who died and the two other cases announced Saturday.

“If we had the ability to test earlier, I’m sure we would have identified patients earlier,” said Duchin, the Seattle and King County health officer.

On Saturday, the Food and Drug Administration took steps to expand testing by speeding up certified hospital laboratories’ ability to create and use their own tests, following complaints from many labs. The FDA also approved a test developed by New York state laboratories, Gov. Andrew M. Cuomo said, making New York the first state able to use its own test.

Alarm has spread in the past few days as health officials in Washington state, Oregon and California reported cases of community transmission — people who were infected by unknown means who had not come in contact with known patients and had not traveled to countries hit by the outbreak.

Another 15 people in the United States have travel-related infections and 47 have been repatriated from Wuhan, China, or a cruise ship where the disease ran rampant.

Given the geographic spread of the emerging cases and the increasing ability of labs to test, experts believe the number of cases identified in the United States is likely to increase rapidly.

“This is a pivot point,” said Scott Becker, chief executive of the Association of Public Health Laboratories. “As the testing increases, what we may uncover is essentially how the virus has marched into America.”

Concerns about the virus have led major companies to begin canceling conferences and travel plans within the United States, which analysts warn will have cascading effects on the country’s hotels, airlines and convention centers.

An unreleased report from a branch of the State Department obtained by The Washington Post on Saturday found roughly 2 million tweets already peddling conspiracy theories about the coronavirus, raising worries about Silicon Valley’s preparedness to combat a surge of dangerous disinformation online.

Trying to avoid panic, Pence said Saturday that the average American does not need to buy face masks because of the coronavirus, echoing worries by health officials that hoarding such supplies may put health workers at risk in coming weeks.

“Seriously people- STOP BUYING MASKS!” the U.S. surgeon general’s official account tweeted Saturday. “They are NOT effective in preventing general public from catching #coronavirus, but if health care providers can’t get them to care for sick patients, it puts them and our communities at risk!”

Asian American leaders have pleaded for the public to stop using xenophobic rhetoric related to coronavirus against Asian American-owned businesses and restaurants, which have suffered in recent weeks.

Some fear is a natural part of the cycle of epidemics, said Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security. “It’s common early on to feel overwhelmed and view the situation as unmanageable, but it’s important to remember that this too shall pass. These precautions health officials are trying to disseminate will start becoming routine. Once people know what they should be doing, I think there will be a level of calm.”

Meanwhile, the outbreak continued to worsen abroad. On Saturday, Italy became the third country — after China and South Korea — with more than 1,000 confirmed coronavirus cases following a week in which the country became the apparent epicenter of Europe’s outbreak. The latest data showed 1,128 people in Italy have been diagnosed with the virus and 29 have died.

More than half of the cases are in the northern region of Lombardy, which includes Milan. But a handful of cases have also popped up as far south as Sicily and Puglia.

Iran reported more than 200 new cases of the virus — as well as nine deaths. Iranian officials said they are preparing for “tens of thousands” of tests. That risks burdening the country’s already weak health-care system — due in part to U.S. sanctions — which has struggled to cope in the last 10 days with a sudden spike in coronavirus infections. The virus has killed 43 people and infected 593 people overall, making Iran’s death toll the highest outside of China. Some analysts question whether the true number is even higher, given the repressive government’s reputation for covering up and controlling information.

The virus’s spread, coupled with such suspicions of a coverup, has fueled panic among the public. Unverified videos shared Saturday showed a group setting fire to a medical clinic in Bandar Abbas in southern Iran. The crowd reportedly thought the clinic had coronavirus patients, according to the Associated Press, citing semiofficial media.

In France — where no one has died but 100 infections have been confirmed — officials on Saturday forbade gatherings of larger than 5,000.

China reported its lowest manufacturing numbers on record for the month of February, as the epidemic-stricken economy ground to an unprecedented standstill.

Ashley Nguyen in Kirkland, Wash., Chico Harlan in Rome, Gerry Shih in Beijing, James McAuley in Paris, and Tony Romm, Alex Horton, Marisa Iati, Anne Gearan, Derek Hawkins and Laurie McGinley in Washington contributed to this report.