All of the deaths have occurred in Washington state, and most were residents of a nursing home in suburban Seattle. The number of infections in the U.S. overall climbed past 100, scattered across at least 15 states, with 27 cases in Washington alone.

"What is happening now in the United States may be the beginning of what is happening abroad," said Dr. Nancy Messonnier of the Centers for Disease Control and Prevention, noting that in China, where the outbreak began more than two months ago, older and sicker people are about twice as likely to become seriously ill as those who are younger and healthier. Most cases have been mild.

The nursing home outbreak apparently seeded the first case in North Carolina, authorities said. A Wake County resident who had visited the Washington state nursing home tested positive but is in isolation at home and is doing well, according to the North Carolina governor's office.

In suburban Seattle, 27 firefighters and paramedics who responded to calls at the nursing home were tested for the virus Tuesday using a drive-thru system set up in a hospital parking area.

Thirty-year-old firefighter Kevin Grimstad took care of two patients Jan. 29 at Life Care Center in Kirkland. He is among 10 from the Kirkland Fire Department who developed symptoms after calls to the nursing facility.

Grimstad, his wife and 6-month-old son have taken turns recovering from fevers, coughs and congestion. They're all feeling better, but wish they knew more about the virus.

"It's crazy. A couple of weeks ago, it seemed like a foreign thing and now we're getting tested," Grimstad said. "If I was exposed a month ago, the problem is more widespread than we know."

In the nation's capital, officials moved on a number of fronts.

A bipartisan $7.5 billion emergency bill to fund the government's response to the outbreak worked its way through Congress.

The Federal Reserve announced the biggest interest-rate cut in over a decade to try to fend off damage to the U.S. economy from the factory shutdowns, travel restrictions and other disruptions around the globe. On Wall Street, stocks rallied briefly on the news, then went into another steep slide, with the Dow Jones Industrial Average losing 785 points on the day, or 2.9%.

"We have seen a broader spread of the virus. So, we saw a risk to the economy and we chose to act," Fed Chairman Jerome Powell said.

Also, the Food and Drug and Administration sought to ease a shortage of face masks by giving health care workers the OK to use an industrial type of respirator mask designed to protect construction crews from dust and debris.

Lawmakers on Capitol Hill expressed skepticism about U.S. health officials' claims that testing for the new virus should be widely available soon. CDC test kits delivered to states and cities in January proved faulty.

Authorities have said labs across the country should have the capacity to run as many as 1 million tests by the end of the week.

But testing so far has faced delays and missteps, and "I'm hearing from health professionals that's unrealistic," Democratic Sen. Patty Murray of Washington state said at a Senate hearing.

The chief of the Food and Drug Administration, Dr. Stephen Hahn, said the FDA has been working with a private company to get as many as 2,500 test kits out to labs by the end of the week. Each kit should enable a lab to run about 500 tests, he said. But health officials were careful about making promises.

"I am optimistic, but I want to remain humble," said Dr. Anne Schuchat of the CDC.

In Washington state, researchers believe the virus may have been circulating undetected for weeks. That has raised fears that there could be hundreds of undiagnosed cases in the area.

But some people who want to be tested for the virus in the state are encountering confusion, a lack of testing options and other problems as health authorities scramble to deal with the crisis.

"The people across my state are really scared. I'm hearing from people who are sick, who want to get tested and don't know where to go," Murray said. "It's unacceptable that people in my state can't even get an answer as to whether or not they are infected."

One lab was already testing for coronavirus in Washington state and a second was scheduled to begin doing so Tuesday.

Amid the rising fears, a school district north of Seattle closed for training on conducting remote lessons via computer in case schools have to be shut down for an extended period, while a private school said it would conduct online-only classes through the end of March.

"We do not feel it is prudent to wait until there is a known case to take action," the school, Eastside Prep in the Seattle suburb of Kirkland, said on its website.

A Department of Homeland Security facility just south of Seattle instructed all its employees to work from home after a worker became ill after visiting the nursing home at the center of the outbreak.

An Amazon employee in Seattle tested positive for the new virus, The Seattle Times reported, citing a message from the company.

Elsewhere around the world, the crisis continued to ebb in China, where hundreds of patients were released from hospitals and new infections dropped to just 125 on Tuesday, the lowest in several weeks. But the crisis seemed to shift westward, with alarmingly fast-growing clusters of infections and deaths in South Korea, Iran and Italy.

Worldwide, more than 92,000 people have been sickened and 3,100 have died, the vast majority of them in China. Most cases have been mild.

"What China shows is that early containment and identification of cases can work, but we now need to implement that in other countries," said Dr. Nathalie MacDermott, an infectious-diseases expert at King's College London.