The United States, Australia and Thailand each reported their first coronavirus-related deaths over the weekend, all in the span of about 12 hours, as the virus continued its rapid spread around the globe.

The covid-19 disease has now killed patients on four continents, with the global death toll climbing toward 3,000 and countries tightening travel restrictions, canceling public events and urging their populations to take health precautions.

In Washington state, health officials said Saturday that a man in his 50s with underlying health conditions died at a hospital in Kirkland, Wash., after testing positive for covid-19.

The patient had no recent travel history or contact with people known to be infected, suggesting he may have been infected through person-to-person transmission, officials said. It was not immediately clear when he was admitted, when his symptoms first appeared or how long it took health officials to test him.

Along with the fatality, officials in the Seattle area confirmed two additional new cases related to a possible outbreak at a long-term nursing home — raising an alarm because the cases involved people considered to be especially vulnerable to infection. One patient is a female health care worker in her 40s who was in satisfactory condition; the other, a female resident in her 70s, is in serious condition, according to state health officials.

Jeffrey S. Duchin, the chief health officer for Seattle and King County, identified the nursing home as Life Care Center in Kirkland, and said he would not be surprised to find additional cases at the facility as an investigation continued. Of Life Care’s more than 108 residents and roughly 180 staffers, Duchin said 27 residents and 25 staff members have shown coronavirus symptoms.

The Centers for Disease Control and Prevention said it was sending a team of experts to Washington to support its investigation.

Earlier Saturday, the Trump administration outlined new travel restrictions affecting Iran, Italy and South Korea in response to the outbreak, and President Trump said he was considering further restrictions across the southern border.

Here are the latest developments:

  • As cases mounted, the White House scrambled to gain control of a rudderless response defined by bureaucratic infighting, confusion and misinformation. “It’s complete chaos,” one senior administration official said.

  • The Food and Drug Administration expanded coronavirus testing by speeding up hospitals’ abilities to test, though some worried the changes fell short in reducing logistical burdens.

  • Misinformation about the disease is proving hard to contain. Roughly 2 million tweets peddled conspiracy theories about the coronavirus over the three-week period when the outbreak began to spread outside China, according to an unreleased report from an arm of the State Department.