At least six Americans were exposed to the Ebola virus during an outbreak in the Democratic Republic of Congo, according to sources cited by CBS News and the BBC.
Health officials said one American was believed to be showing symptoms, while three others were reported to have experienced high-risk exposure or contact.
It remains unclear whether any of the Americans have been infected.
The US Centers for Disease Control and Prevention said it was supporting the safe withdrawal of a small number of Americans directly affected by the outbreak.
The World Health Organization has declared the outbreak a public health emergency of international concern amid growing fears of wider regional spread.
Authorities in DR Congo have reported around 350 suspected cases and at least 91 deaths linked to the outbreak.
The outbreak is centered in eastern DR Congo’s Ituri province and involves the Bundibugyo strain of Ebola, for which there are currently no approved vaccines or treatments.
The CDC said the risk to the American public remains low but confirmed it was closely monitoring developments.
US officials have also issued a Level Four travel advisory warning against travel to DR Congo.
Sources told health news outlet STAT that the US government was exploring options to move affected Americans to a quarantine site, potentially including a US military base in Germany, though officials have not confirmed the plan.
Uganda has also confirmed cases linked to the outbreak, including one death.
The WHO has urged DR Congo and Uganda to strengthen cross-border screenings and surveillance measures to limit transmission.
Health agencies warned the outbreak could be significantly larger than currently detected due to gaps in reporting and surveillance.
Neighbouring Rwanda announced tighter border screening measures with DR Congo as a precaution.
Nigeria also said it was closely monitoring the evolving situation.
Jean Kaseya, director general of the Africa Centres for Disease Control and Prevention, urged communities to follow public health guidance, particularly regarding funeral practices linked to Ebola transmission.
“We don't want people infected because of funerals,” he told the BBC World Service.
Officials said community awareness and regional coordination remain central to containing the outbreak.