Updated 3:50 PM
Lawmakers are pointing to a new Inspector General report to answer why security at Washington, D.C.'s Navy Yard—the site of Monday's shooting—failed to stop a lone gunman bent on a rampage that ultimately killed 12 people.
House Armed Services Committee Chairman Rep. Howard "Buck" McKeon, R-Calif., said the Pentagon IG report, released to the House committee, showed "critical flaws" in security efforts geared toward contractors. A redacted version of the report was released to the public Tuesday.
"Yesterday, the Inspector General forwarded a copy of their report on access to Naval Installations to the Armed Services Committee," McKeon said in a statement. "The report details critical flaws in the practice of contracting access control for military installations to non-governmental personnel."
Thirty-four-year-old Aaron Alexis, the alleged shooter, was a Navy reservist working as a civilian contractor. He possessed a "common access card," officials told NBC News, along with an additional a security clearance because of his access to classified information.
McKeon noted that the report was released independent of Monday's shooting, and that its impact on scrutiny of security efforts was "coincidental," but said he found it "relevant to physical security on military installations."
McKeon also said the report contained information relevant to Wednesday's committee hearing on the impact deep defense cuts were having on the department. The Pentagon has borne the brunt of the automatic spending cuts known as sequestration that were implemented when Congress failed to reach a budget deal. Thirty-seven billion dollars was stripped from the Pentagon budget this year, with $54 billion to follow in 2014, totaling $500 billion over 10 years.
The Pentagon has pushed back against further cuts in this latest round of budget negotiations, but after faring better than expected during the first round of cuts, it was thought to be an uphill battle.
Capitol Hill aides told NBC News that, "The report itself is certainly concerning" and that it will be "relevant to what happened [Monday]."
Secretary of the Navy Ray Mabus announced on Twitter Tuesday that he ordered a review of security at all Naval and Marine Corps installations.
A senior defense official told NBC News that the first review would be a "quick look" at the bases' existing physical security requirements, and the second would be a more comprehensive look at the physical requirements, including swipe card access, security around the bases' perimeter, and patrols.
The second would also include a look into personal security requirements, including an individual's likelihood to comply with security standards, including protecting classified information.
Secretary of Defense Chuck Hagel is also ordering a separate review of "physical security and access at all DoD installations worldwide," a senior Pentagon official told NBC News.
Rick Mason, an administrative specialist working in the Naval Sea Systems Command headquarters when the shooting took place Monday, told NBC's Andrea Mitchell that workers participated in emergency drills "three or four times a year," geared primarily toward fire drills and not specifically active shooter drills.
Mason described the entry procedure at the headquarters, which houses around 3,000 workers.
"When you first get to the gate at the street entrance, you have to show your badge in order to get in. Once you get in, then also you have to swipe your badge in order to get into the building. And also you have to show your badge to the security guard once you're inside." Mason described occasional bag checks at times of heightened security and did not mention the use of magnetometers.
"And from that point on, you know, you are OK to go ahead into your working area and begin your work for that day," Mason said.
NBC's Jim Miklaszewski, Courtney Kube, and Kelly O'Donnell contributed reporting.
Read the full Inspector General report here.