One more person has died of the new coronavirus in the Seattle, Washington area, bringing the total number of fatalities there to 10, health officials said on Wednesday, and new confirmed cases were reported around the two most populous cities in the United States - four near New York and six in Los Angeles.

The first California death from the virus was also announced on Wednesday. The person, an elderly adult with underlying health conditions, was the second confirmed case of the respiratory disease called COVID-19 in Placer County in Northern California, local health officials said.

The total number of coronavirus cases in the greater Seattle area climbed to 39, up from 27 cases and nine deaths a day earlier, the Washington State Health Department announced.

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The Seattle area has the largest concentration of coronavirus cases detected to date in the US. Several cases were connected to a long-term care facility for the elderly in the Pacific Northwest state.

In New York City, three family members and a neighbour of an infected man have tested positive, bringing the total in New York state to six, officials said. About 1,000 people in suburban Westchester County north of the city where the family lives were under self-quarantine orders because of possible exposure to the virus, New York Governor Andrew Cuomo said.

"We are, if anything, being over-cautious," Cuomo said.

Empty shelves that usually contain cleaning products in a store in New York City in the United States [Brendan McDermid/Reuters]

On the West Coast, Los Angeles officials announced six new confirmed travel-related cases in Los Angeles County, including three people who had been to northern Italy, one of the places hardest hit in the global outbreak.

Of the six, only one has been hospitalised. The other five are recovering in home isolation.

Los Angeles County declared a local emergency and a public health emergency in order to expand and hasten preparedness efforts.

In Washington, DC, US lawmakers reached bipartisan agreement on an $8.3bn emergency bill to help fund efforts to contain the virus, a congressional aide said. The bill is expected to be introduced in the US House of Representatives later on Wednesday.

Once the full House approves the bill, the Senate is expected to act quickly so President Donald Trump can sign the measure into law, putting funds into the pipeline to fight the virus.

More than $3bn would be devoted to research and development of coronavirus vaccines, test kits and therapeutics. There are currently no approved vaccines or treatments for the fast-spreading illness.

In a bid to also help control the spread of the virus outside the US, $1.25bn would be set for international efforts, the aide said.

Medics transport a man on a stretcher into an ambulance at the Life Care Center of Kirkland, a long-term care facility linked to several confirmed coronavirus cases, in Kirkland, Washington, US [David Ryder/Reuters]

The administration is working to allow laboratories to develop their own coronavirus tests without seeking regulatory approval first, US Health Secretary Alex Azar said.

The latest data from the US Centers for Disease Control and Prevention (CDC) listed 129 confirmed and presumed cases in the US, up from the previous 108. They included 80 reported by public health authorities in 13 states plus 49 among people repatriated from abroad, according to the CDC website.

Those figures do not necessarily reflect Wednesday's updates from three states.

Classes cancelled

On Tuesday, officials said a man in his 50s who lives in a New York City suburb and works at a Manhattan law firm tested positive for the virus, the second identified case in the state.

The four new cases there include three family members of the man, who is hospitalised, and a neighbour. Health authorities said one of the man's children was a student at Yeshiva University, which cancelled classes as a precautionary measure.

The hospitalised patient had not travelled to countries with large numbers of cases. The first New York case, reported last week, was a woman who had returned from Iran, where at least 92 people have died.

Cuomo said about 300 students from New York's college systems, SUNY and CUNY, were being recalled from five hard-hit countries - China, Italy, Japan, Iran and South Korea - and would be flown on a chartered plane and then be quarantined for 14 days.