Computers were stolen from the U.S. compound in Benghazi during the 2012 terrorist attack, potentially exposing sensitive information and putting those who worked with American officials at risk, according to sources in Washington and on the ground in Libya.

"They took computers, computer devices. And I saw M-16 rifles, American rifles. I know they are American --we don't have them, we just have AK-47s -- and a suitcase," said a Libyan who reported he had witnessed the attack.

He described what he saw on condition his identity was concealed.

His account of computers being stolen was confirmed by two sources in Washington familiar with the investigation into the attack. Fox News was told the computers are believed to be unclassified, and likely used for schedules and meetings as well as to document and process emails.

The hard drives would also contain a history of user names.

"That's a huge deal," former CIA officer Charles S. Faddis said, adding the incident would prompt an immediate damage assessment by the State Department.

"It would be a very formal process and it would be done with great urgency. Anytime there is any classified system or just any computer system that's fallen out of our hands, yeah. Big deal. It wouldn't be something you'd get to eventually. It would be a front-burner thing."

While it is not clear if there was a direct connection, Fox News was told that after the computers were taken, some of the locally employed staff in Libya received death threats via text message.

"With relative ease, they could get everything that's on that computer," Faddis said. "Which would be not just sort of Word files but stored communications, I mean stored messages - all kinds of things. Phone lists, contact lists, lists of personnel."

On Friday, a State Department spokesperson was asked about the status of the missing computers, and threats against locals who worked with U.S. personnel.

"We are not aware of any specific threats in this instance,"said spokesperson Marie Harf.

"Obviously, unfortunately local employed staff do face threats from time to time overseas, but again, not aware of anything related to this."

Harf said information about computers is largely classified, adding "But I can say that during the evacuation of the special mission compound to the (CIA) Annex, all classified computers were safely removed by the DS (Diplomatic Security) agents. No classified information was compromised."

In her book, "Hard Choices", former Secretary of State Hillary Clinton justified the lack of security in Benghazi "..because there was no classified processing at the diplomatic compound, there were no Marines posted there..."

On Tuesday, Fox News followed up with the State Department in an effort to reconcile what appeared to be a conflict between Harf's statement that classified computers were recovered, and Clinton's description of the consulate as an operation that did not handle classified information.

"I said no classified computers had gone missing in Benghazi," Harf said. "I think where the -- a little bit of confusion lies here is, there were not -- when we talk about classified information, there weren't classified documents...If there were, you know, small classified computers, that's different than handling classified documents or materials. I think from a security perspective, we look at those a little differently."

"There is a significant issue as to what they decide is classified and what they decide is unclassified," Faddis said "...In other words, there is a significant chance that you would have stuff on unclassified computers that were in the possession of the Department of State that would still have information that was pretty sensitive and that probably an entity like CIA would say should have been classified...the Department of State is inclined to have more information in an unclassified context typically than CIA is comfortable with."

Another State Department spokesman also said the consulate did not have a “permanent classified presence.”

Harf confirmed there was an FBI investigation of the unclassified computers. "There's an investigation ongoing led by the FBI to determine what, if any, materials, documents, computers -- anything went missing, or was taken during the attack. That investigation's ongoing,” she said. “I don't have an update for you, given that it's ongoing."

A State Department spokesman also said classified networks were available to the consulate.