By midday Saturday, one of them, Dr. Kent Brantley, had landed in Georgia, a source with the relief organization Samaritan's Purse tells PEOPLE.
Amber Brantly, wife of Dr. Brantly, released the following statement Saturday: "It was a relief to welcome Kent home today. I spoke with him, and he is glad to be back in the U.S. I am thankful to God for his safe transport and for giving him the strength to walk into the hospital. Please continue praying for Kent and Nancy [Writebol], and please continue praying for the people of Liberia and those who continue to serve them there."
Both patients were due to arrive at Dobbins Air Reserve Base before being taken to Emory University Hospital in Atlanta for treatment, Emory and Pentagon officials told CNN.
One of them "will arrive in the next several days," Dr. Bruce Ribner, who heads the isolation unit at Emory, said on Friday, "then a second patient will be coming a few days after that."
Both contracted the disease while working with infected patients in Liberia, the charities they were working for say.
It will be the first time someone with a documented case of Ebola has been on American soil, according to the Atlanta-based Centers for Disease Control and Prevention, but there is no cause for alarm, officials say.
"The safety and security of U.S. citizens is our paramount concern," the state department said. "Every precaution is being taken to move the patients safely and securely, to provide critical care en route on a non-commercial aircraft, and to maintain strict isolation upon arrival in the United States."
Those precautions include an "isolation pod" aboard the aircraft, the state department said.
Centers for Disease Control and Prevention
"Although other U.S. hospitals are equipped to safely manage a patient with Ebola virus disease," she says, "Emory has added additional protection to ensure the safety of our healthcare team and other patients."
The patients have been identified by the charities they were working for as Dr. Kent Brantly, 33, of Fort Worth, Texas, and Nancy Writebol, 59, of Charlotte, North Carolina. Writeboi is expected to arrive in the U.S. in the coming week.
Brantly was treating Ebola patients for the international relief group Samaritan's Purse, while Writebol screened them before they were admitted.
Writebol was there with the missionary group SIM, which is working with Samaritan's Purse to combat Ebola in Liberia. She and Brantly worked in the same hospital, but did not know each other. They were both in serious condition as of this morning, according to Samaritan's Purse.
On Wednesday, Brantly turned down a potentially life-saving experimental treatment so Writebol could have it, Samaritan's Purse said in a statement.
"An experimental serum arrived in the country, but there was only enough for one person," Franklin Graham, president of the charity said.
"Dr. [Kent] Brantley asked that it be given to Nancy Writebol," said Graham, who did not release the name of the serum. "Even as he battles to survive Ebola, this heroic doctor is still focused on the well-being of others."
Below are some answers to common questions about Ebola from the CDC:
What is Ebola?
Also known as Ebola hemorrhagic fever, the disease causes high fever, vomiting, diarrhea and internal bleeding.
Is there a cure?
Unfortunately there is no vaccine or cure.
What precautions are being taken on the patients' transport to the US?
The CDC is providing a containment system, which is a portable, tent-like device that can be used in an aircraft for the evacuation," says the CDC. This system provides a high level of protection for medical staff and air crew who will be traveling with the patient.
What precautions will Emory undertake to make sure other patients and health-care workers are protected?
Although other U.S. hospitals are equipped to safely manage a patient with Ebola virus disease, Emory has added additional protection to ensure the safety of our healthcare team and other patients.
What would public health officials do to contain an outbreak if a new American case were reported?
The proven way to stop any outbreak is to quickly identify all new cases, get them into proper isolation and medical care, and proactively follow-up all potential contacts for signs of disease. The same type of work that CDC, along with other domestic and international partners, are doing in Guinea, Liberia and Sierra Leone, would work here.
For more information, visit the Center for Disease Control website.
Reporting by MICHELLE BOUDIN