Members of Congress were left stunned during a briefing from law enforcement about their failure to prepare for the insurrection at the US Capitol earlier this month, two members who attended a House Appropriations Committee briefing told CNN on Tuesday, with one saying it was “dumb luck” more people didn’t die. House Appropriations Committee Chair Rosa DeLauro, a Connecticut Democrat, said in a phone call with CNN that members were “shaking their heads in disbelief” throughout the briefing about the security breakdown in the lead up to January 6. During that briefing, acting US Capitol Police Chief Yogananda Pittman admitted her department knew there was a “strong potential for violence” targeting Congress, but did not take appropriate steps to prevent it. DeLauro said the revelation left her stunned and multiple federal law enforcement agencies failed by not acting on the intelligence they had. “They had the information. They did not act on it. And a question that I have, and one that I think we need to get to the bottom of, is who made the decision not to act?” DeLauro told CNN. “People said today that there was ample evidence, that the intelligence agencies had ample evidence, that an angry mob was going to descend on Washington with Congress’ meeting to certify the election as the intended target,” DeLauro added. After participating in the hearing, Rep. Matt Cartwright, a Pennsylvania Democrat, told CNN, “It was only by pure dumb luck that elected officials, staffers and more Capitol policemen were not killed.” Cartwright said his theory of why there was not enough action to prepare was “that people were more worried about optics more than they were worried about security.” Cartwright said he directly asked those briefing the committee whether concerns about how security preparations would look was a reason for not acting. “I got no denials, and I got a couple of confirmations,” he told CNN, declining to say who specifically confirmed that optics were a motive behind inaction. The briefing came as US Capitol Police officers debate whether to hold a no-confidence vote targeting department leaders who were working on the day of insurrection, including Pittman. One source told CNN that Pittman was the operational chief the day of the siege at the Capitol and “never took control of the radio or commanded officers what to do in any way, shape or form.” Officers have told CNN that they felt abandoned and betrayed by the department’s leadership. According to prepared remarks, Pittman told lawmakers that Capitol Police knew two days before the insurrection that militia and White supremacist groups would be at the Capitol on January 6, and some of those people planned to be armed. Pittman outlined four things that made the department ill-equipped to respond to the attack: a lack of manpower, not having the right equipment on hand or easily accessible, a lack of consistency in following the process for sealing the building and communication over radios and the public address system being hard to hear during the attack. CNN has attempted to speak to some of the Republican lawmakers who attended the briefing. Rep. Kay Granger of Texas, the top Republican on the committee, described the briefing as a “critical first step” and joined her Democratic colleagues in calling out the failure to act on intelligence that could have prevented the attack. “While many questions remain, it is clear that the failure was not due to a lack of intelligence, but rather a failure to properly act on this intelligence. This is unacceptable and left our law enforcement men and women on the ground unprepared for the danger they would face. These heroes not only deserve our gratitude for successfully keeping Members and staff safe, they deserve answers and a commitment to do better,” Granger said in a statement. Rep. David Valadao, a California Republican, said in a statement to CNN, “Today’s security briefing with the House Appropriations Committee on the events of January 6 was very informative, and I hope the committee continues to hold them.” DeLauro said members were not given a clear answer when they repeatedly asked for who was responsible for the lack of preparedness and response. “No one would answer the question,” DeLauro said to CNN, suggesting that it may be worth having one individual in charge going forward to avoid the kind of miscommunication that occurred the day of the attack. The Connecticut Democrat said there was no specific line of questioning around tours given prior to January 6 during the briefing, other than a mention from the FBI that all matters relating to the genesis of the insurrection are being investigated. She closed her remarks at the briefing by saying tours are something that need examined, and something she believed was being investigated. Cartwright shared that there was a “good discussion” about how to more “carefully vet” security forces, particularly those tasked with defending the Capitol.