This post has been updated.

Four State Department managers were disciplined Wednesday, following sharp criticism from independent investigators that the department did not do enough to protect a group of Americans killed in an eight-hour siege in September of U.S. government compounds in Benghazi, Libya.

The highest-ranking official, Eric Boswell, the head of the Diplomatic Security Bureau, resigned effective immediately, the State Department announced late Wednesday. The three others were responsible for various aspects of embassy security and planning for Libya and the Middle East.

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