More than 20 CIA operatives were on the ground when the US consulate in Benghazi, Libya, came under attack, resulting in the death of four Americans, including Ambassador Chris Stevens.
Sources have told CNN that during the September 11, 2012, attack on the consulate, 35 Americans, including about 21 CIA agents were working at the consulate and in a CIA base known as the annex, which was a mile away from the diplomatic mission.
Seven hours after the attack on the consulate, the secret CIA annex building came under fire, killing two former Navy SEALs. It is yet unknown how the attackers knew about what was supposed to be a secret CIA facility.
Sources have also told CNN that the CIA is involved in an unprecedented attempt to keep the spy agency's Benghazi secrets from leaking out.
In order to prevent any leaks, some CIA operatives involved in the agency's missions in Libya are being intimidated and threatened by the agency, with some being subjected to frequent, even monthly polygraph examinations.
Congress is worried about the lack of information and the pressure to silence CIA operatives.
"I think it is a form of a cover-up, and I think it's an attempt to push it under the rug, and I think the American people are feeling the same way," said US Rep. Frank Wolf, whose district includes CIA headquarters in Langley, Virginia.
"We should have the people who were on the scene come in, testify under oath, do it publicly, and lay it out. And there really isn't any national security issue involved with regards to that," he said.