Hillary Clinton's campaign was slow to respond Friday to the FBI announcing it had found additional emails related to the private and unauthorized server she maintained when she worked at the State Department.

The first real reaction from the Democratic nominee's camp came from her running mate, Sen. Tim Kaine, D-Va., who would only say, "gotta' read a little more, gotta' read a little more."

Another member of Clinton's campaign staff declined to respond when asked to comment on the latest development, and would only say he had "no idea" what the agency was talking about.

FBI Director James Comey informed Congress this week that his agency had found a stash of emails possibly related to its earlier investigation of the Democratic nominee's private server.

"In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to the investigation," he wrote in a letter addressed to Democratic and Republican lawmakers.

"I am writing to inform you that the investigative team briefed me on this yesterday, and I agreed that the FBI should take appropriate investigative steps designed to allow investigators to review these emails to determine whether they contain classified information, as well as to assess their importance to our investigation," Comey said.

The Democratic nominee, her aides and her traveling press corps were in the air en route to Cedar Rapids, Iowa, when the news broke. They had no access to WiFi, and many were out of the loop until touchdown. When Clinton disembarked from her campaign plane, she ignored questions from reporters and declined to say anything about her emails.

She has been dogged for months by questions about her private emails, and whether she compromised national security by operating an unsecured homebrew server.

Clinton said in December 2014 that she turned over more than 30,000 emails to the State Department. However, she also said at the time that she deleted roughly 32,000 emails from her private servers.

Clinton and her team argued they deleted nearly half of the emails on her private servers because the messages were personal, and that they didn't qualify as work-related.

Much of the FBI's investigation into Clinton's use of a private server focused on recovering those deleted emails.

Comey, who ultimately recommended no charges be brought against Clinton, said in July his investigators "discovered several thousand work-related" notes among the trove of thousands of deleted emails.

The FBI chief also revealed some of the deleted emails contained classified information, contrary to Clinton's earlier claims.

"From the group of 30,000 emails returned to the State Department, 110 emails in 52 email chains have been determined by the owning agency to contain classified information at the time they were sent or received," he said.

On Friday, Comey's letter to Congress breathed new life into a scandal that many thought ended when he recommended that no charges be brought against Clinton.