Citing a senior State Department official it did not identify, CNN reported Eric Boswell, assistant secretary of diplomatic security, and Charlene Lamb, deputy assistant secretary of state for international programs, submitted their resignations. The official said a State Department employee in the Near East Affairs bureau also resigned, CNN reported.
Boswell and Lamb were responsible for security at the Benghazi mission.
Secretary of State Hillary Clinton says she accepts all 29 proposals in a highly critical report on the fatal U.S. mission attack in Benghazi, Libya.
The independent Accountability Review Board report said parts of the State Department suffered from "systemic failures" in their response to the Benghazi terrorist threat and had "grossly" inadequate security, relying on local militias, which left U.S. diplomats and other personnel highly vulnerable, an unclassified summary of the report posted on the State Department's website indicated.
The report faulted State Department officials in Washington for ignoring requests from the U.S. Embassy in Tripoli for more guards and safety upgrades to the mission -- and said intelligence agencies and the White House made a mistake in initially saying the Sept. 11 attack that killed Ambassador Christopher Stevens and three other Americans sprang from public outrage against an anti-Islamic video produced in the United States.
The report cited two key State Department bureaus -- Diplomatic Security and Near Eastern Affairs -- for particular criticism for inadequate security.
"Systemic failures and leadership and management deficiencies at senior levels within two bureaus" resulted in security "that was inadequate for Benghazi and grossly inadequate to deal with the attack that took place," the report said.
It said the temporary, lightly defended compound where Stevens died had "profoundly weak" physical security and lacked "proactive senior leadership" for security.
The fact that inexperienced staff members worked there for short periods led to "diminished institutional knowledge, continuity and mission capacity," the report said.
"Americans in Benghazi and their Tripoli colleagues did their best with what they had, which, in the end, was not enough to prevent the loss of lives," the nearly 40-page report said.
The study was conducted by a board appointed by Clinton and led by retired U.S. Navy Adm. Mike Mullen, a former chairman of the Joint Chiefs of Staff, and Thomas Pickering, a longtime U.S. diplomat including the U.S. ambassador to the United Nations.
Despite the broad security failures, the report did not single out any individual officials as violating procedures and did not recommend any disciplinary action.
Clinton said in a letter to the Senate and House foreign relations committees she accepted "every one" of the report's recommendations for improvement, most notably its recommendation for security improvements for front-line posts in conflict zones and other dangerous countries.
Clinton said the State Department had already begun to address lapses the report outlined.
The report "provides a clear-eyed look at serious, systemic challenges," she said in her letter, released to reporters Tuesday night.
Officials told The Washington Post Clinton would ask Congress to transfer $1.3 billion allocated to Iraq for additional Marine guards, diplomatic security personnel and security improvements at overseas U.S. missions.
The report called on Congress to fully fund the request for additional security funds.
"For many years the State Department has been engaged in a struggle to obtain the resources necessary to carry out its work with varying degrees of success," the report said. A result has been decisions that sacrifice security for savings, it said.
The two foreign relations committees are to hear testimony Thursday on the report from Deputy Secretary of State William J. Burns and Deputy Secretary of State for Management and Resources Thomas R. Nides.