Hillary Clinton and Donald Trump clashed in the second presidential debate Sunday over his taped remarks about sexual aggression toward women and his taxes, as well as her private email server and her husband's alleged sexual misconduct.

The event was held at Washington University in St. Louis. CNN's Anderson Cooper and ABC News' Martha Raddatz moderated.

Questions were taken from social media and the undecided voters that composed the audience. The candidates had two minutes to answer the questions.

The debate began, sans handshake between the candidates, after Clinton won the coin toss.

Towards the beginning of the debate the candidates addressed the 2005 video of Trump's lewd comments about women and sexual assault to Billy Bush, then of Access Hollywood. Trump called it "locker room talk" before he referred to Bill Clinton's history with women.

In response, Clinton did not address the attacks on her husband, instead quoting Michelle Obama: "When they go low, you go high."

Clinton said she never questioned the fitness to serve of prior Republican presidential candidates. "Donald Trump is different," she said.

Trump also used Clinton's favor with the Democratic establishment against her.

He referred to the Democratic nomination as rigged in Clinton's favor. The race against her opponent, Sen. Bernie Sanders of Vermont, was not "fair and square." Trump also said he was surprised to see Sanders "sign on with the devil."

If Trump were to assume the Oval Office, Trump said he would call for a "special prosecutor" to look into Clinton's usage of a private email server.

Anderson Cooper asked if Trump used his losses he reported on his taxes in the 1990s to his advantage. "Of course I do. Of course I do," Trump said.

When addressing foreign policy, the candidates talked about Russia, Syria and ISIS.

Clinton said "leverage" is needed for negotiations with Russia when it comes to Syria and the Syrian Civil War. She also said she believed in the usage of special forces and called Trump a "gift to ISIS and the terrorists."

On the same topic, Trump said he "hadn't spoken and disagreed" with his running mate Mike Pence. "We have to worry about ISIS," Trump said. He also said Russia and the Assad regime were also fighting ISIS.

The candidates also discussed recent hackings and leaks. Clinton said they were aiding Trump's campaign.

"Maybe there is no hacking," Trump said . "I know nothing about Russia."

Trump also repeatedly said he would not have had people in Iraq and that he opposed the Iraq War, even though Trump has said he supported the war in the past.

At the end of the debate, the candidates were asked to name one positive thing each respected in the other. Clinton answered by complimenting Trump's children, saying they are "incredibly able and devoted."

"I think that says a lot about Donald," Clinton said.

Trump said that Clinton, "doesn't quit. She doesn't give up. I respect that." He also called her a "fighter."

Terry Nguyen contributed to this piece.

Reach Staff Reporter Hannah Vega here, or follow her on Twitter.