Jacquelyn Martin/AP
White House press secretary Josh Earnest speaks about the resignation of Secret Service Director Julia Pierson amid a recent White House security breach, Oct. 1, 2014.
However, White House press secretary Josh Earnest did not specify the countries in which they are being held, or whether the Islamic State jihadist group was involved.
"There is at least one other hostage that is held in the region," Earnest said in his daily briefing. "We are aware of other American hostages being held in the region."
When pressed, Earnest refused to give specifics on the case or cases.
"We have avoided discussing the individual cases of Americans who are being held hostage," he said. "I'm not going to get into the specific discussions of the cases of the individuals who have been held hostage. Principally because we don't believe it's in their best interest for me to discuss them publicly."
Earlier on Tuesday, the White House confirmed the death of Kayla Mueller, a 26-year-old American aid worker who was held by the Islamic State (also known as ISIS or ISIL). Mueller had been described as the group's final US hostage. ISIS has executed other American hostages that were in their custody.