CHICAGO (AP) — Officials across the country curtailed many elements of American life to fight the coronavirus outbreak on Sunday, with health officials recommending that groups of 50 or more don’t get together and a government expert saying a 14-day national shutdown may be needed.

Governors were closing restaurants, bars and schools as the nation sank deeper into chaos over the crisis. Travelers returning home from overseas trips were stuck in line for hours at major airports for screenings, causing them to be crammed into just the kind of crowded spaces that public health officials have been urging people to avoid.

In a sign of the impending economic gloom on the horizon, the Federal Reserve slashed its benchmark interest rate to near zero. President Donald Trump sought to calm a jittery nation by declaring that the government has “tremendous control” over the situation and urging people to stop the panic buying of grocery staples that has depleted the shelves of stores around the country. Gun stores started seeing a similar run on weapons and ammunition as the panic intensified.

As Americans struggled to come to terms with how to change their daily habits, the Centers for Disease Control and Prevention issued a dramatic recommendation: Because large events can fuel the spread of the disease, it said gatherings of 50 people or more should be canceled or postponed throughout the country. It added that, at any event, proper precautions should be taken, including making sure people are washing their hands and not getting too close.

But in a sign of the difficulty of striking the right balance, the statement from the CDC also said the recommendation does not apply to “the day to day operation of organizations such as schools, institutes of higher learning, or businesses.”

Even before the warning, parts of the country already look like a ghost town, and others are about to follow as theme parks closed, Florida beaches shooed away spring breakers, Starbucks said it will accept only drive-thru and takeout orders and the governors of Ohio and Illinois ordered bars and restaurants shuttered. California’s governor asked the state’s bars and restaurants to do the same, but didn’t order it. New York City, New Jersey and elsewhere are considering similar measures.

“The time for persuasion and public appeals is over,” Illinois Gov. J.B. Pritzker said. “This is not a joke. No one is immune to this.”

His decision came hours after Dr. Anthony Fauci, the federal government’s top infectious disease expert, said he would like to see a 14-day national shutdown imposed to prevent the virus’s spread.

“I think Americans should be prepared that they are going to have to hunker down significantly more than we as a country are doing,” said Fauci, a member of the White House task force on combating the spread of coronavirus. He heads the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.

There is no indication Trump is considering such a move.

The worldwide outbreak has sickened more than 162,000 people and left more than 6,000 dead, with thousands of new cases confirmed each day. The death toll in the United States climbed to 64, while infections passed 3,200.

Meanwhile, harsh criticism rained on Trump and his administration Sunday from state and local officials over long lines of returning international passengers at some U.S. airports that could have turned them into coronavirus carriers as they tried to get home.

Chicago Mayor Lori Lightfoot lambasted the administration for allowing about 3,000 Americans returning from Europe to be stuck for hours inside the customs area at O’Hare International Airport on Saturday, violating federal recommendations from the Centers for Disease Control and Prevention that people practice “social distancing.”

The passengers, many of them rushing home because of fears they would be stuck in Europe, were screened for coronavirus symptoms before they were allowed to leave the airport.

Long lines also formed Saturday in Boston, Dallas and others of the 13 airports that are accepting return flights from Europe.

“People were forced into conditions that are against CDC guidance and are totally unacceptable,” Lightfoot said.

Elizabeth Pulvermacher, a University of Wisconsin student, arrived Saturday at O’Hare from Madrid, where she had been studying and spent hours in line. The customs process made her feel “unsafe,” she said.

“The whole idea is getting rid of the spread of coronavirus, but there were hundreds and hundreds of people in very close proximity,” Pulvermacher said.

Dr. Robert Murphy, executive director of Institute for Global Health at Northwestern University, said he was “appalled” by what he saw Saturday at nearby O’Hare.

“If they weren’t exposed to COVID-19 before, they probably are now. From a public health perspective, this is malpractice,” Murphy said in a statement Sunday. “The lack of preparation and concern is unfathomable.”

But the situation improved markedly Sunday at O’Hare and elsewhere. Acting Homeland Security Secretary Chad Wolf said wait times are down to 30 minutes after processes have been adjusted to better handle the influx and extra personnel sent to the airports that are “funneling” passengers returning from overseas.

Bailey Miles, a 20-year-old sophomore at Taylor University in Indiana, arrived also from Madrid fearing the worst, but she got through customs and a health screening in about an hour. She said officials seemed to have learned their lesson from Saturday, when some of her friends returned.

“The employees were really helpful, had positive attitudes and had a lot of grace,” she said. She said a woman even passed out snacks.

At Newark Liberty International Airport in New Jersey, Amanda Kay said she was asked to keep her distance from other passengers when she arrived from Paris at Newark Liberty International Airport in New Jersey.

“They wanted 50 people at a time. So the first 50 people got off, and they asked us to keep a large distance between ourselves,” she said. “We showed them the first form and then as we walk there’s a person who has the scan for your temperature. And then you go through Customs and then that was it.”

Going forward, Wolf said he could not rule out a future halt to air travel within the U.S. Fauci said earlier Sunday on television that halting domestic travel had been discussed, though not seriously.

For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia. The vast majority of people recover.