– The coronavirus outbreak could kill 100,000 to 200,000 Americans, the U.S. government's top infectious-disease expert warned on Sunday as family members described wrenching farewells through hospital windows with dying loved ones.

Faced with that grim projection and the possibility even more could die without measures to keep people away from one another, President Donald Trump extended federal guidelines recommending people stay home for another 30 days until the end of April.

Trump's extension of the original 15-day guidelines was a stark reversal just days after he said he hoped the economy could restart in about two weeks and came after Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, made the dire prediction of fatalities, adding that millions in the U.S. could become infected.

"We want to make sure that we don't prematurely think we're doing so great," Fauci said.

By Sunday night, the U.S. had over 140,000 infections and 2,400 deaths, according to the running tally kept by Johns Hopkins University, though the true number of cases is thought to be considerably higher.

Worldwide, more than 720,000 infections were reported, and deaths topped 33,000, half of them in Italy and Spain, where the health system is at the breaking point.

New York state — where the death toll passed 1,000 — remained the epicenter of the U.S. outbreak, with the vast majority of the deaths in New York City. But spikes in infections were recorded around the country, not only in metropolitan areas but in Midwestern towns and Rocky Mountain ski havens. West Virginia reported its first death, leaving only two states — Hawaii and Wyoming — with none.

The virus is moving fast through nursing homes, assisted living facilities and other places that house elderly or otherwise vulnerable people, spreading "like fire through dry grass," New York Gov. Andrew Cuomo said.

Since the U.S. saw its first major outbreak earlier this month — centered at a nursing home in Kirkland, Wash., — a stream of similar facilities have battled infections.

A week ago, the Centers for Disease Control and Prevention said 147 nursing homes in 27 states had patients with COVID-19. The problem has only worsened since.

In Woodbridge, N.J., a nursing home relocated all of its residents after two dozen were confirmed infected and the rest were presumed to be. In Louisiana, at least 11 nursing homes have reported cases. In Mount Airy, Md., a death linked to the virus was recorded in a home where 66 people were confirmed infected.

Residents' loved ones, kept away to try to slow the spread, fear they may not get to say goodbye. "I have a feeling that I very likely may never see my mother again," said James Preller, whose mother, Ann Preller, 94, is a resident at Peconic Landing, a Long Island retirement community, where seven have died recently.

Worry for the poorest was being echoed around the world. In India, a lockdown covering the country's 1.3 billion people has put untold numbers out of work and left many families struggling to feed themselves. Tens of thousands in New Delhi were forced to flee their homes, with no way to pay the rent, journeying back to their native villages.

Though the U.S. leads the world in reported cases, five other countries have higher death tolls: Italy, Spain, China, Iran and France. Italy reported more than 750 new fatalities Sunday, bringing the country's total to nearly 10,800. But the number of new infections showed signs of easing, with officials expressing cautious optimism that the most severe shutdown in the industrialized West is showing results.

Italy's civil protection agency said more than 5,200 new cases were recorded in the past 24 hours, the lowest number in four days, for a total of almost 98,000 infections.

Spain moved to tighten its lockdown and ban all nonessential work as it hit another daily record of almost 840 dead. Spain's overall official toll was more than 6,500.

Egypt shut its beaches. Police in the Philippines stepped up arrests of quarantine violators, and more tourists were evacuated from Mount Everest.

Russia ordered borders to close on Monday, Moscow all but confined its 12 million residents to their homes, and the head of the Russian Orthodox Church called on believers to stay away and pray at home.