A U.S. official says CIA employees are believed to be among the dead in Wednesday's suicide bombing inside a base in eastern Afghanistan.
A former senior CIA officer who was stationed at the base said a combination of agency officers and contractors operated out of the remote outpost with the military and other agencies.
The CIA has not yet commented or confirmed the deaths.
A congressional official said it was not clear how many of the victims were assigned to the CIA.
The officials spoke on condition of anonymity because they were not authorized to discuss the matter with the media.
U.S. officials said the attack occurred at Forward Operating Base Chapman in Khost province, killing eight American civilians and wounding others.