Updated 8:20 p.m. ET
(CBS News)Four State Department officials resigned Wednesday after the release of a scathing report about security lapses at the U.S. Consulate in Benghazi, Libya.
An attack there on September 11th killed four Americans, including Ambassador Chris Stephens.
The State Department's chief of security Eric Boswell, his deputy Charlene Lamb, an official in the Near East Division that oversees Libya, and yet another official all resigned. The report called security at the U.S. post in Benghazi "grossly inadequate to deal with the attack."
Career diplomat Thomas Pickering, who ran the review board that produced the report, said: "Frankly, the State Department had not given Benghazi the security, both physical and personnel resources, it needed."
The investigation found that senior State Department officials ignored requests from Ambassador Chris Stephens for more guards and security upgrades at the Benghazi compound.
The report also says the State Department did not have a clear picture of the security situation in Benghazi, and should have realized the compound was a target. And it criticized Libyan militias who were assigned to protect the post but disappeared when dozens of armed attackers approached on September 11.
Other failings include an "inadequate" number of State Department security agents and a lack of technical staff: Boxes of security cameras sat unused because no one knew how to install them.
Admiral Mike Mullen, who co-chaired the investigation, said: "The buildings at Special Mission Benghazi did not meet Department standards for office buildings in high-threat areas and, in a sense, fell through the cracks bureaucratically."
He said it was not reasonable for Secretary of State Hillary Clinton to have knowledge of specific security arrangements in Benghazi.
Sec. Clinton released a letter saying she accepted all of the panel's 29 recommendations. Following the Benghazi attacks, she has already sent hundreds of Marine guards to U.S. posts, and is requesting more funding from Congress.
On Thursday, two of Sec. Clinton's deputies will answer questions from Congress about the review board's findings. Lawmakers say they still want Sec. Clinton -- who had to drop out of planned testimony recently due to a concussion and an illness -- to testify when she is well.
The report says Ambassador Stephens did have security concerns but he did not ask for the mission in Benghazi to be shut down after resources were denied.
Investigators made clear Stephens had responsibility for deciding what security was necessary on the ground.