Washington (CNN) -- Action has been taken against "the individuals involved" in posting a sensitive Transportation Security Administration screening manual on the Internet, Homeland Security Secretary Janet Napolitano told members of Congress on Wednesday.
"The security of the traveling public has never been put at risk," Napolitano told the Senate Judiciary Committee, and "the document that was posted was an out-of-date document.
"Nonetheless, the posting of it did not meet our own standards for what should be available on the Net and not available on the Net," she said. "So we have already initiated personnel actions against the individuals involved in that."
Pressed on who those individuals were by the committee chairman, Sen. Patrick Leahy, D-Vermont, Napolitano said "the individual involved was a contractor. Some of the supervisors ultimately were in TSA."
She did not say how many people were determined to have been involved in the posting of the manual, which outlined screening procedures for law enforcement officers, diplomats, prisoners, federal air marshals and others.
The agency has instituted an internal review of the incident "to see what else needs to be done so that the incident never recurs," Napolitano said. In addition, the TSA has asked the inspector general to conduct an independent review "to supplement and complement what we are doing."
However, other agencies have been notified that the security of their documents may have been compromised, other Department of Homeland Security officials told the Senate Homeland Security and Governmental Affairs Committee.
The practice of posting sensitive documents has been suspended, said Rand Beers, undersecretary of national protection for the TSA, and David Heyman, the agency's assistant secretary for policy, under questioning from Sen. Susan Collins, R-Maine. Those involved are on administrative leave pending review, they said.
Sen. Jon Kyl, R-Arizona, suggested to Napolitano that a "red team" damage assessment be done -- a review by someone outside the agency to determine what advantage a potential enemy could have gained from the information and recommend what procedures or actions are necessary to minimize the damage.
Napolitano said the agency is considering it. "I think one of my first questions has been well, what exactly was put out there that wasn't available either by observation of airport checkpoints or the like. But indeed we may, if it is ascertained that there was some information not otherwise available that was put out, I think the red teaming issue is something that I would consider, absolutely."
In a statement Tuesday night, the TSA sought to minimize the impact of the unintentional release -- calling the document "outdated," "unclassified" and unimplemented -- while saying that it took the incident "very seriously," and "took swift action" when it was discovered.
Congressional critics, meanwhile, lambasted the agency and called for an independent investigation.
"Undoubtedly, this raises potential security concerns across our transportation system," House Homeland Security Chairman Rep. Bennie Thompson, D-Mississippi, and Rep. Sheila Jackson Lee, D-Texas, wrote in a letter to TSA Acting Administrator Gale Rossides.
Collins, the ranking member of the Senate Homeland Security Committee, called the release of the information "shocking" and reckless Tuesday. "This manual provides a road map to those who would do us harm," she said.
At issue is a 93-page manual giving instruction to airport screeners on how to screen individuals. It also gives details on how screening is conducted and the limitations of x-ray machines.
The TSA posted the manual on a federal business opportunities Web site that provides information for government contractors, and redacted sensitive parts. But the redacted information was not properly protected, and the information was restored by people familiar with the computer program.
The TSA said the posted manual -- dated May 28, 2008, with an implementation date of June 30, 2008 -- was never implemented and has been revised six times, although it did not elaborate on the extent of the revisions.
"While the document does demonstrate the complexities of checkpoint security, it does not contain information related to the specifics of everyday checkpoint screening procedures," the TSA said Tuesday. "The traveling public should be assured that appropriate measures have been put in place to ensure the continued implementation of a strong security screening program," it said.
The TSA said it removed the report as soon as it learned of the problem. But it was too late. The full, unredacted version of the report appeared on at least one Web site on Sunday, and was even more widely distributed Tuesday.