WASHINGTON (AP) — Five employees at the Transportation Security Administration are on administrative leave.

They'll stay off the job while investigators try to find out why sensitive guidelines about airport passenger screening were posted on the Internet.

An assistant Homeland Security secretary told senators that an investigation is under way, and that the employees involved have been taken off duty. A TSA official later said five employees are on administrative leave.

At a separate hearing, Homeland Security Secretary Janet Napolitano told senators that the department is taking steps to make sure this never happens again. She added that "the traveling public was not at risk."

Among other things, the document outlined who is exempt from certain additional screening measures. And it offered examples of identification documents that screeners accept.