A drive containing data on potentially every official in the Clinton administration was likely stolen from the National Archives and Records Administration in 2009, according to emails deleted by Hillary Clinton but recovered and released Thursday by the State Department.

The information was conveyed by Blake Roberts, a deputy White House counsel for President Obama, in a message that made it to Hillary Clinton's private server in April 2009. "The National Archives alerted me that they cannot account for a 2 terabyte hard drive containing electronic records from the Clinton administration," Blake wrote. "They believe it was stolen. NARA has an identical copy of the drive, which it is analyzing."

Roberts said the drive, which contained information equivalent to approximately 900 million single-spaced pages, went missing between Jan. 30 and Mar. 24. He added that there was a "90 percent probability" it held personal information, including dates of birth and Social Security numbers, on all of Clinton's White House staff.

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"Two terabytes is a very very large amount of data," Roberts noted. "The drive may contain a wide range of memos, emails, and other electronic documents from the Clinton White House. All the material is unclassified, except for three documents."

"The NARA Inspector General is investigating the breach. NARA is working to determine what content was on the drive. NARA estimates that it will take about a week to determine the full range of individuals whose personal information was compromised; at that time NARA will determine whether to formally notify those individuals. Right now, NARA's efforts to ascertain the contents of the drive are focused on identifying whose personally identifiable information was compromised," he added.

The National Archives determined later in the year that 15,750 individuals had been affected. It is not known whether the drive was ever found.