A second person died of the coronavirus in Washington, according to local health authorities. It is also the second death from the disease in the U.S. Three more people in the county have also been hospitalized as a result of the disease. There are now 10 confirmed cases of illnesses from the new coronavirus in King County, Washington.

A man in his 70s died at EvergreenHealth Medical Center in Kirkland — the same hospital where the death of a man in his 50s was announced yesterday. Both men had underlying health problems. The three other new cases are two women, one in her 80s and one in her 90s, and a man in his 70s. All three have other health issues. They are in critical condition.

These new cases, including the death, are in people who were residents at Life Care, a nursing facility. Earlier today, health officials also said that two more people, men in their 60s, had also been hospitalized for illness from the novel coronavirus. A total of six people who have connections to Life Care have been formally diagnosed with COVID-19, the disease caused by the new virus.

Genetic sequencing suggests the virus may have been circulating for six weeks. Two samples of the virus — one from a person who traveled to Snohomish County in January from China, and one from a recently-diagnosed high school student with no history of travel to an affected area or contacts with known cases — were compared, and the sequence was nearly identical, according to Trevor Bedford, a computational biologist at Fred Hutchinson Cancer Research Center in Seattle.

Bedford says his work is preliminary, and it’s possible there are other explanations besides community spread. However, he believes that an alternative explanation is unlikely, because of an unusual variant on one of the genes.

The team at the @seattleflustudy have sequenced the genome the #COVID19 community case reported yesterday from Snohomish County, WA, and have posted the sequence publicly to https://t.co/tbVb4MAGpy. There are some enormous implications here. 1/9 — Trevor Bedford (@trvrb) March 1, 2020

“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,” Bedford said on Twitter. Until last week, people with symptoms of COVID-19 weren’t tested for the virus unless they’d traveled to an area where the virus was circulating or had contact with a confirmed case. The testing criteria were expanded after a public backlash — and cases with unknown causes were found.

COVID-19 causes a fever, a cough, and shortness of breath. More than 89,000 people have been infected worldwide and more than 3,000 have died.