WASHINGTON (AP) ― Three State Department officials resigned under pressure Wednesday, less than a day after a damning report blamed management failures for a lack of security at the U.S. diplomatic mission in Benghazi, Libya, where militants killed the U.S. ambassador and three other Americans on Sept. 11.

The resignations came as lawmakers expressed anger and frustration over the findings of an independent review panel, and the State Department struggled to find a balance between protecting its diplomats while allowing them to do their jobs connecting with people in high-risk posts.

An Obama administration official said Eric Boswell, the assistant secretary of state for diplomatic security, Charlene Lamb, the deputy assistant secretary responsible for embassy security, and Raymond Maxwell, the deputy assistant secretary of state who oversees the Maghreb nations of Libya, Algeria, Tunisia and Morocco. The official spoke on condition of anonymity because he wasn’t authorized to discuss personnel matters publicly.

The issue of security at the mission and the deaths of the Americans became a political hot potato with Republicans accusing the Obama administration, and especially U.N. Ambassador Susan Rice of playing down the possibility it was a terrorist attack. Eventually Rice was forced to withdraw her name from consideration to replace Hillary Rodham Clinton as secretary of state during President Barack Obama’s second term.

Rice had appeared on numerous TV talk shows the Sunday after the attack and linked it to an anti-Islamic U.S. film. Those comments came after evidence already pointed to a distinct militant attack. The department declined immediate comment on the resignation of the officials whose decisions had been criticized in the unclassified version of the Accountability Review Board’s report released Tuesday.

The board’s co-chairman, retired Adm. Mike Mullen, told reporters that the board had not determined that any officials had “engaged in willful misconduct or knowingly ignored his or her responsibilities,”

But Mullen, a former Joint Chiefs of Staff chairman, added, “We did conclude that certain State Department bureau level senior officials in critical levels of authority and responsibility in Washington demonstrated a lack of leadership and management ability appropriate for senior ranks in their responses to security concerns posed by the special mission.”

Mullen said the mission’s security fell through bureaucratic cracks caused in part because buildings were categorized as temporary. The report said that budget constraints had caused some officials to be more concerned with saving scarce money than in security.

Co-chairman Thomas Pickering, a retired ambassador, said the personnel on the ground in Benghazi had reacted to the attack with bravery and professionalism. But, he said, the security precautions were “grossly inadequate” and the contingent was overwhelmed by the heavily armed militants.

“They did the best they possibly could with what they had but what they had wasn’t enough,” Pickering said.

Pickering and Mullen spoke shortly after briefing members of Congress in private. Lawmakers from both parties emerged from the sessions with harsh words for the State Department.

“My impression is the State Department clearly failed the Boy Scout motto of be prepared,” said Sen. John Barrasso, a Republican.

“They failed to anticipate what was coming because of how bad the security risk already was there. ... They failed to connect the dots,” he said. “They didn’t have adequate security leading up to the attack and once the attack occurred, the security was woefully inadequate.”

Rep. Adam Schiff, a member of the House intelligence committee, said security was “plainly inadequate, intelligence collection needs to be improved, and our reliance on local militias was sorely misplaced.”

“These are not mistakes we can afford to make again,” he said.

The House intelligence committee chairman, Rep. Mike Rogers, a Republican, said the report laid bare “the massive failure of the State Department at all levels, including senior leadership, to take action to protect our government employees abroad,” and complained that no one was being held accountable.

Rogers also said he was dissatisfied with the lack of progress in finding the attackers.

Lamb, the deputy assistant secretary of state for diplomatic security who was in charge of embassy protection, testified in October before the House Oversight and Government Reform Committee and defended the security measures.

“I made the best decisions I could with the information I had,” Lamb said at the time. “We had the correct number of assets in Benghazi at the time of 9/11.”

She also told Rep. Dan Burton, a Republican, that she rejected requests for more security in Benghazi, instead training “local Libyans and army men” to provide security, a policy in force at U.S. diplomatic facilities around the world.

Pickering and Mullen set the stage for public hearings set for Thursday in Congress. Scheduled to testify were Deputy Secretary of State William Burns, who is in charge of policy, and Deputy Secretary of State Thomas Nides, who is in charge of management.

Clinton was to have appeared at Thursday’s hearings, but canceled after fainting and sustaining a concussion last week while recovering from a stomach virus. Clinton is under doctors’ orders to rest.