At least six Americans were exposed to a terrifying strain of Ebola virus in the Democratic Republic of Congo — and the US Centers for Disease Control and Prevention is expected to withdraw the possibly infected individuals.

The Americans were exposed to the deadly virus amid a recent outbreak tearing through central Africa and spreading into major urban capitals, sources with international aid organizations told CBS News.

Of the six people, three faced high-risk exposure or contact, and one is symptomatic, the outlet reported.

It’s unclear whether they currently remain in Congo. But, the CDC said in a statement on Sunday that it was working to coordinate the “safe withdrawal of a small number of Americans who are directly affected in outbreak areas.”

It’s not yet known whether the Americans will be brought back to the US for a quarantine or isolated in another region for monitoring.

The agency said it has also placed travel health notices for Congo and Uganda to help Americans planning travel to either country in the near future, and has ordered its offices in the African nations to support global response efforts.

“The overall risk to the American public and travelers remains low,” the CDC said, noting that no cases of the illness have spread to the US.

The World Health Organization slapped a “public health emergency of international concern” label on the deadly Bundibugyo Ebola virus outbreak following a surge of cases across Congo and now in Uganda.

As of Sunday, there are reports of 10 confirmed cases and 336 suspected cases of the specific Ebola strain, including 88 deaths. There are two confirmed cases, including one death in Uganda, in people who traveled from DRC, the CDC said.

There are “significant uncertainties to the true number of infected persons and geographic spread” and a “limited understanding of the epidemiological links” between victims, according to the WHO.

The agency further warned that the data “all point towards a potentially much larger outbreak than what is currently being detected and reported.”

Bundibugyo Ebola virus has a startlingly high death rate ranging from 25 to 50%, and involves hallmark symptoms such as fever, headache, vomiting, severe weakness, abdominal pain, nosebleeds, and vomiting blood.

There is no vaccine for the illness, and treatment involves supportive care.

Describing the crisis as an “extraordinary” threat, UN health chiefs sounded the alarm over unusual clusters of community deaths and four healthcare worker deaths.