The FBI is examining additional emails related to Hillary Clinton‘s use of a private email server four months after closing its investigation, the bureau’s director said in a letter to lawmakers on Friday, a surprise twist in a turbulent campaign just 11 days before election day.

In a note to congressional committee chairs, FBI director James Comey said that the FBI had discovered additional emails relevant to the investigation into Clinton’s server and agents were examining the emails to determine whether they contain classified information.

The newly discovered emails were found on at least one device belonging to longtime Clinton aide Huma Abedin and her husband, former congressman Anthony Weiner, as part of an investigation into Weiner’s sexting scandal, multiple news outlets reported citing law enforcement officials.

“In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to the investigation,” said Comey. “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.”

There was no additional information about what information the emails contain or how long the investigation could take.

Clinton called on the FBI to release all the information it had about the additional emails.

“We are 11 days out from perhaps the most important national election in our lifetimes. Voting is already underway in our country,” Clinton told reporters hours after Comey’s letter became public. “So the American people deserve to get the full and complete facts immediately. [Comey] himself has said he doesn’t know whether emails referenced in his letter are significant or not. I’m confident, whatever they are, will not change the conclusion reached in July.”

Abedin and Weiner separated after it was reported in August that the former congressman allegedly sent sexually suggestive photos to a minor. Previously, Weiner sent lewd photos to women on numerous occasions, ending his career in Congress and his subsequent campaign for New York City mayor in two separate scandals.

The FBI found the additional Clinton emails as part of an investigation into Weiner’s alleged habits, news outlets reported.

Clinton’s use of a private email server during her time as Secretary of State has become a central issue of the campaign. After a months-long investigation, the FBI decided in July not to recommend criminal charges against Clinton, saying there was no prosecutorial precedent for doing so.

At question in the investigation was the former secretary of state’s handling of classified information. The FBI found that in a handful of instances, classified email was discovered on Clinton’s personal server, but that they were not clearly marked as classified.

The additional emails are a political pitfall for Clinton, whose campaign had hoped to coast into election day with a sizable victory after watching Donald Trump’s campaign slowly collapse under the weight of sexual assault allegations and erratic statements.

On Friday, Clinton’s campaign chairman said that the FBI should promptly release more detailed information about the emails, calling it “extraordinary” that to “see something like this just 11 days out from a presidential election.”

“The Director owes it to the American people to immediately provide the full details of what he is now examining,” said campaign chairman John Podesta. “We are confident this will not produce any conclusions different from the one the FBI reached in July.”

Trump’s campaign manager, Kellyanne Conway gloated about the revelation on Friday afternoon.

Republicans were quick to attack Clinton for the revelation, widely seen as a new opening against Clinton as she appears set on a path to victory on Nov. 8. “Hillary Clinton’s corruption is on a scale we have never seen before. We must not let her take her criminal scheme into the Oval Office,” Trump said.

“Yet again, Hillary Clinton has nobody but herself to blame,” House Speaker Paul Ryan in a statement. “She was entrusted with some of our nation’s most important secrets, and she betrayed that trust by carelessly mishandling highly classified information.”

Senate Judiciary Committee chairman Chuck Grassley said that he was surprised by the news and said he asked for the FBI for more details.

“The letter from Director Comey was unsolicited and, quite honestly, surprising. But it’s left a lot more questions than answers for both the FBI and Secretary Clinton,” Grassley said in a statement. “Congress and the public deserve more context to properly assess what evidence the FBI has discovered and what it plans to do with it.”

The Clinton campaign was caught off guard by the news on Friday. “I’ve got to read more,” Sen. Tim Kaine, Clinton’s running mate said, campaigning in Florida. “I’ve got to read a little more.”

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