Seventeen American passengers who were aboard the cruise ship on the Atlantic Ocean that faced a hantavirus outbreak were on their way to the United States on Sunday night and were expected to land in Nebraska early Monday, health officials said.

There, they will be monitored at the country’s only federally funded quarantine center.

The passengers, flying on a U.S. government medical flight, were expected to land at Offutt Air Force Base near Omaha, according to the Centers for Disease Control and Prevention. They will be transported to the National Quarantine Unit at the University of Nebraska Medical Center/Nebraska Medicine in that city, health officials said. At the center, the passengers will be observed around the clock by a volunteer team of doctors and nurses, the agency said.

Two of the passengers on the flight were traveling in specialized biocontainment units out of an abundance of caution. One passenger had mild symptoms, and another tested “mildly PCR positive” for the Andes virus, according to the Department of Health and Human Services.

Hantavirus is a rare family of viruses carried by rodents. The Andes virus, a strain of hantavirus, was identified by the World Health Organization as the one that affected the cruise passengers. It can be transmitted between people who have had close contact. So far, the rare Andes strain has killed three people who were passengers on the cruise and has caused five others to fall ill, according to W.H.O. officials.

A team of epidemiologists and other medical professionals from the C.D.C. met the American passengers when their cruise ship docked off the Canary Islands of Spain on Sunday and conducted exposure risk assessments.

The quarantine unit in Omaha consists of 20 single-occupancy rooms with individual ventilation systems that continually expel air. It was designed specifically to safely shelter and monitor people who have been exposed to extremely serious infectious diseases.

The passenger who tested positive for the virus but does not have symptoms will be transported to a specialized biocontainment unit upon arrival, while other passengers will go to the National Quarantine Unit for assessment and monitoring, said officials with Nebraska Medicine, a health care network in Omaha.

The biocontainment unit was activated in 2014 to receive U.S. citizens with Ebola virus who had been medically evacuated from Africa. In 2020, doctors there cared for some of the first Americans diagnosed with COVID-19.

It is unclear how long the passengers will be quarantined for. Physicians at the Omaha center are working with federal partners as well as the state and county health departments.

Several other states, including Georgia, California and Arizona, are monitoring U.S. residents who disembarked the cruise ship before the outbreak was identified and had already returned home.

Seven Americans disembarked from the ship on April 24 and came back to the United States on commercial flights, Dr. Jay Bhattacharya, the C.D.C.’s acting director, said Sunday on CNN’s State of the Union. None had symptoms at the time of their travel, he said, so officials had not seen a need to alert other travelers on those flights or attempt to trace other contacts.

“At this time, the risk to the American public remains extremely low,” the C.D.C. said in a statement on Friday.

Apoorva Mandavilli contributed reporting.