It was the first time State has formally deemed any of Clinton's emails classified at that level, reserved for information that can cause "exceptionally grave" damage to to national security if disclosures.
State did not provide details on the subject of the messages, which represent seven email chains and a total of 37 pages. However, State spokesman John Kirby said they are part of a set the intelligence community inspector general told Congress contained information classified for discussing "Special Access Programs."
"These documents were not marked classified at the time they were sent," Kirby said in a statement. He said State is still looking into whether they should have been considered classified at the time they were created.
"I'm not going to speak to the contents of the traffic," the spokesman said.
State was ordered by a federal judge to complete its public release of Clinton's emails by today, but said last week it will not be able to meet that deadline. About 1,000 of the remaining 9,000 pages are expected to be released this evening, Kirby said.
Thus far, about 1,300 emails from Clinton's account have been deemed classified, most at the lowest level, "confidential."
In past email releases, the classified information was deleted and the rest of the messages were released. However, the messages deemed "top secret" will not be published even in part, Kirby said.
Read more: Here
