Clinton had earlier in the day completed two campaign rallies in the state without making a mention of the email controversy.
Following an event in Des Moines, a campaign aide led Clinton's traveling press into the choir room at the high school in Des Moines where Clinton had just finished speaking. A podium was set up under bright lights with six American flags in the background and a sign with Clinton's campaign logo, Stronger Together, on the front.
Clinton noted that Americans across the country are already voting and said that it is "imperative" that Comey explain the issue "without delay."
"We don’t know all the facts," Clinton said. "Even Director Comey noted that this information may or may not be significant, so lets get it out."
Comey informed congressional leaders Friday that his agency will make new inquiries related to the private email server Clinton used while secretary of state to see whether classified material was compromised.
At issue are newly discovered emails found on a computer seized during an investigation of disgraced former Rep. Anthony Weiner (D-N.Y.), who is married to senior Clinton aide Huma Abedin. The couple are now separated.
Asked about reports of Abedin's involvement, Clinton acknowledged that she had heard those "rumors."
“We don’t know what to believe,” Clinton said. “That’s why it’s incumbent upon the FBI director to tell us what they’e talking about.”
At stops in Cedar Rapids and Des Moines, Clinton blasted Republican Donald Trump for his treatment of women.
“This is a man who relishes making women feel terrible about themselves,” Clinton said here after recounting Trump years ago bragging to radio personality Howard Stern about “inspecting” contestants in the dressing rooms of beauty pageants he owned.
“He goes after the dignity and self-worth of women, and I don’t think there’s a woman anywhere who doesn’t know what that feels like,” Clinton said at an earlier rally in Cedar Rapids.
Both were billed as “women win” early vote rallies in the battleground state of Iowa.
Clinton was joined in Cedar Rapids by a slate of national women’s rights leaders, including the president of the Planned Parenthood Action Fund, Cecile Richards; president of NARAL Pro-Choice America, Ilyse Hogue; and president of Emily's List, Stephanie Schriock.
“They have a lot of experience standing up to bullies, which is why they’re especially dear to me,” Clinton said.
Clinton also accused Trump of running a “scorched-earth” campaign designed to deter women, minorities and young people from voting.
News related to the FBI action broke while Clinton was in the air, flying from an airport near her home in Westchester County, N.Y., to Iowa. Senior aides to Clinton spoke to reporters on the plane, who were unaware at the time of the development.
The only sign of the controversy at the outdoor rally in Cedar Rapids was scattered protesters outside yelling, “Lock her up" — a familiar refrain at Trump rallies among supporters who argue that Clinton was let off the hook by the FBI.