A second person has died from the coronavirus in the United States, authorities have said.
The victim, a man in his 70s, died on Saturday in Washington state as researchers said the Covid-19 virus may have been circulating in the Seattle area for weeks.
The death follows that of a man in his 50s, with authorities saying both had underlying health conditions and were being treated at a hospital in Kirkland, Washington.
Authorities in the Seattle area said two more people had been diagnosed with the Covid-19 virus, both men in their 60s who were in critical condition, and two healthcare workers in California were also diagnosed.
Elsewhere, authorities announced a third case in Illinois and the first cases in New York state as worried Americans swarmed stores to stock up on basic goods such as bottled water, canned foods and toilet paper.
As the fallout continued, US Vice President Mike Pence and Health and Human Services Secretary Alex Azar sought to reassure the American public that the federal government is working to make sure state and local authorities are able to test for the virus.
Both said during a round of TV talk show appearances on Sunday that thousands more testing kits had been distributed to state and local officials, with thousands more to come.
“They should know we have the best public health system in the world looking out for them,” Mr Azar said, adding that additional cases will be reported and the overall risk to Americans is low.
As Americans prepared, researchers at the Fred Hutchinson Cancer Research Centre and the University of Washington said they had evidence the virus may have been circulating in the state for up to six weeks undetected.
This could mean there are hundreds of undiagnosed cases in the area.
They posted their research online but it was not published in a scientific journal or reviewed by other scientists.
Trevor Bedford, an associate professor who announced the preliminary findings on the virus in Washington state, said on Twitter on Saturday that genetic similarities between the state’s first case on January 20 and a case announced on Friday indicated the newer case may have descended from the earlier one.
The January 20 case was the first known case in the US ad Mr Bedford said: “I believe we’re facing an already substantial outbreak in Washington State that was not detected until now due to narrow case definition requiring direct travel to China.”
There are now more than 89,000 cases of Covid-19 worldwide and about 3,000 deaths.