11:04 p.m.A summary of closing statements:

"If you believe that our country's problems and the threats that we face in this world can only be met with new thinking, new and fresh approaches, then I ask you to join my campaign," O'Malley says. "We will not solve our nation's problems by resorting to the divisive ideologies of our past or by returning to polarizing figures from our past."

"I've heard a lot about me in this debate and I'm going to keep talking and thinking about all of you because ultimately I think the president's job is to do everything possible, everything that she can do to lift up the people of this country, starting with our children and moving forward," Clinton says. She argues she has spent her life looking for ways to even the odds and level the playing field for everyone.

Get Breaking News Delivered to Your Inbox

Sanders points to issues of income inequality, campaign finance, a lack of guaranteed health care for all Americans, high rates of child poverty and no guaranteed family and medical leave. "That's not the America that I think we should be, but in order to bring about the changes that we need we need a political revolution. Millions of people are going to have to stand up, turn off the T.V., get involved in the political process and tell the big money interests that we are taking back our country," he says.

10:55 p.m.Dickerson asks all three candidates to name a crisis in their life that suggests they have been tested for the challenge of being president.

Clinton points to her role in advising President Obama to initiate the raid that killed al Qaeda leader Osama bin Laden.

There was no certainty attached to it, the intelligence was by no means absolute, we had all kinds of questions that we discussed and at the end I recommended to the president that we take the chance to do what we could to find out whether that was bin Laden and to finally bring him to justice. It was an excruciating experience," she said

O'Malley says he doesn't believe there is a crisis at the state or local level that one can point to as evidence they are ready to be a commander in chief, but he says he learned "certain disciplines" that he believes are directly applicable to the job of being president.

"I have been tried under many different emergencies...I know how to manage people in a crisis and be very clear about the goal of protecting human life," he says.

Sanders points to his role in crafting legislation to reform the Veterans' Affairs Hospital system after a series of scandals plagued the agency in 2014.

"I could only get two Republican votes," he says of his original bill. "I had to go back and start working on a bill that wasn't the bill that I wanted...I lost what I wanted but I had to stand up and come back and get the best that we could."

10:40 p.m. Sanders gets a question about whether his desire to have a single-payer healthcare system is realistic given that it's a $1 trillion industry in America.

"It's not going to happen tomorrow," he says, "and it's probably not going to happen until we have campaign finance reform" and insurance companies have less influence over elections.

But he stands by it, and says "single-payer system is the way to go."

Clinton says she "waited" for the revolution on single-payer healthcare, but says it never came. But she says now the focus should be on improving the Affordable Care Act and stopping Republicans from repealing it.

She knocks Sanders for wanting to turn healthcare over to the states, saying, she would not want Iowa Gov. Terry Branstad in charge of her healthcare.

10:35 p.m. Sanders glosses over giving details on how states offer free tuition at public colleges and universities even though many are running deficits.

"I think they're going to be pretty smart because I think a lot of states will do the right thing and those who don't will pay a heavy penalty," he says.

O'Malley argues a better goal is debt-free college.

10:30 p.m. Lots of agreement among the candidates that there needs to be reform in the criminal justice system as an answer to larger issues of race inequality. O'Malley and Sanders both talk about steps that they have taken or want to take to address racial disparities in the prison system.

10:25 p.m. Sanders weighs in on his famous remark from the last Democratic debate -- that "the American people are sick and tired of hearing about your damn emails!"

"I was sick and tired of Hillary Clinton's email, I am still sick and tired of Hillary Clinton's email," he says, joking that after what he said, stories about the email scandal disappeared from the front pages. He says he would prefer to be talking about issues like the disappearing middle class, income inequality, and a lack of paid family and medical leave in the U.S.

"We've gotten off of Hilary's emails, good. Let's go to the major issues facing America," he says.

"I agree completely," Clinton says in response. "I couldn't have said it better myself."

10:17 p.m.The candidates spar over the issue of gun control, and Clinton goes after Sanders' support for a 2005 bill that granted legal immunity to gun manufacturers. Sandres said he would favor reversing immunity and doing even more on gun control.

"I want to see it improved and expanded. I want to see us do away with the gun show loophole," he says.

Asked whether the vote was a mistake, he says, "There were parts of that bill which I agreed with, parts I disagreed with."

O'Malley jumps in to accuse Clinton of being on "three sides" of the gun issue, and argued that in 2008, "You were portraying yourself as Annie Oakley and saying we don't need those regulations."

"There's a big difference in leading by polls and leading by principle," he says.

Sanders cuts in to remark that Baltimore - the city where O'Malley once served as mayor - "is not one of the safest cities in America."

10:07 p.m. O'Malley joins Sanders in attacking Clinton's plan for Wall Street reform as insufficient.

"It was greeted by many as 'weak tea,'" he says. "It is weak tea. It is not what the people expect of our country. We expect that our country will protect the main street economy from excesses on Wall Street. And that's why Bernie's right - we need to reinstate Glass-Steagall." He's referring to the Depression-era law that separated commercial and investment banking and was repealed in 1999.

10:03 p.m.Clinton argues that voters know she will not be beholden to Wall Street even though she accepts donations from people in that sector. She points to her record as a senator, where she introduced legislation to reign in compensation, give shareholders more control, and says she told Wall Street that what they were doing to the mortgage market was "bringing our country down."

She has released a plan she says will help prevent another taxpayer-funded bailout.

Her response, according to Sanders: "Not good enough." He points to the fact that he doesn't have a super PAC and won't be beholden to special interests.

9:56 p.m.The debate shifts to the issue of immigration reform. O'Malley calls Donald Trump an "immigrant-bashing carnival basher," and adds, "our symbol is the Statue of Liberty it is not a barbed-wired fence."

Clinton is asked how she can go further on immigration reform than President Obama has gone even though his proposals are in limbo in the court system.

"I know the president has appealed the decision to the Supreme court," she said, referring to the case involving Mr. Obama's 2014 immigration actions to protect as many as five million illegal immigrants.

Clinton she has reviewed the law, and she said she's convinced "that the president has the authority that he attempted to exercise with respect to Dreamers and their parents."

9:44 p.m. The Affordable Care Act gets a lot of love from both Clinton and Sanders. Clinton calls it a "great accomplishment" and Sanders says it was a "step forward."

Both argue that the law can be improved, particularly to bring down the price of drugs for Americans. Clinton said earlier it's "outrageous" that the U.S. government does not have an opportunity to negotiate for lower drug prices under Medicare.

"We have to go after price gouging and monopolistic practices and get Medicare the authority to negotiate," she says.

Sanders says, "I want to end the international embarrassment of the United States being the only major country on earth that doesn't' guarantee healthcare to all people as a right and not a privilege.

9:43 p.m.Sanders said he wouldn't make the tax rate as high as the level under President Dwight Eisenhower, which Sanders said was at 90 percent. "I'm not that must of a socialist compared to Eisenhower," he joked.

9:39 p.m. O'Malley defends his call for debt-free college by pointing to the fact that he was able to hold Maryland's public college tuition rate steady for four years. He turned the conversation to an entitlement he says the U.S. can no longer afford: A lower income tax rate and lower rate on capital gains.

9:35 p.m. O'Malley, who was the first candidate to call for the U.S. to take in 65,000 Syrian refugees, said he stands by that figure despite the fact that some of the terrorists involved in the attacks in Paris might have come into Europe with refugees fleeing Syria.

Clinton has also called for the U.S. to take in 65,000 Syrian refugees. She said, "I do not want us to in any way inadvertently allow people who wish us harm come into our country," Clinton said, adding that the U.S. has to look at other global challenges including in the South China Sea and with Russia.

9:30 p.m. A few foreign policy nuggets:

Clinton says Congress should "update" the Authorization for the Use of Military Force (AUMF) to make sure the president has the authority that is needed for the fight against the ISIS. The administration is still relying on a 2002 authorization for the fight against the Islamic State of Iraq and Syria.

Sanders calls for "major reform in the military making it more cost effective but also focusing on the real crisis that faces us."

On taking in refugees fleeing conflict in Syria, he says, "I believe that the United States has the moral responsibility with Europe, with Gulf Countries like Saudi Arabia, to make sure that when people leave countries like Afghanistan and Syria...of course we reach out."

But, he added, "What the magic number is, I don't know, because we don't know the extent of the problem."

9:28 p.m Clinton argues it's "not particularly helpful" to say the U.S. is at war with radical Islam because the U.S. needs to reach out to Muslim countries. She does say it's fair to talk about "Islamists who clearly are also jihadists." Many Republicans have criticized President Obama for not using the term, "at war with radical Islam."

Sanders weighs in: "I don't think the term is what's important."

O'Malley argues the appropriate term is "radical jihadis," but most important is to get Muslim Americans to speak out against violence committed in the name of Islam.

9:22 p.m O'Malley gets a question about whether or not the world is too dangerous a place for a governor with no foreign policy experience. He pivots to an implicit attack on Clinton without using her name.

"Libya is now a mess. Syria is a mess. Iraq is a mess. Afghanistan is a mess. As Americans we have shown ourselves to have the greatest military on the face of the planet but we are not so very good at anticipating threats," he said.

9:17 p.m. Clinton once again says her vote in favor of the Iraq was a "mistake," but argued it is a mistake to fixate on that one vote.

"We need to understand it and realize that it has antecedents to what happened in Iraq and we have to continue to be vigilant about it," she said.

Sanders said his disagreement with Clinton runs deeper than just the Iraq War vote, and pointed to a long U.S. history of pushing for regime change in countries like el Salvador and Guatemala.

"These toppling of governments, regime changes have unintended consequences," he said. "On this issue I'm a little bit more conservative than the secretary and I am not a great fan of regime change."

9:13 p.m. Sanders blames the "disastrous" Congressional vote in favor of the war of Iraq for the deteriorating situation in the Middle East.

He called for an international coalition, including Muslim countries, to fight ISIS.

"I think that was one of the worst foreign policy blunders in the modern history of the United States," he said.

9:11 p.m. Clinton is asked whether the Obama administration -- herself included -- underestimated the threat from ISIS. She placed the blame on former Iraqi Prime Minister Nouri al-Maliki.

"I think that what happened when we abided by the agreement that George W. Bush made with the Iraqis to leave by 2011 is that an Iraqi army was left that had been trained and was prepared to defend Iraq. Unfortunately Nouri al-Maliki, the prime minister, set about decimating it," she said, before pointing to the violence in neighboring Syria.

"I don't think that the Untied States has the bulk of the responsibility. I really put that on Assad and on the Iraqis and on the region itself," she said.

9:08 p.m.The candidates are invited to give one-minute opening statements about the attacks in Paris. Some excerpts:

Sanders: "Together leading the world this country will rid our planet of this barbarous organization called ISIS. I'm running for president because as I go around this nation I talk to al to of people and what I hear is people's concern that the economy we have is a rigged economy. People are working longer hours for lower wages...on top of that we have a corrupt campaign finance system."

Clinton: "Our prayers are with the people of France tonight but that is not enough. We need to have a resolve that will bring the world together to root out the kind of radical jihadist ideology that motivates organizations like ISIS, a barbaric, ruthless, violent jihadist terrorist group. This election is not only about electing a president, it's also about choosing our next commander in chief, and I will be laying out in detail what I think we need to do with our friends and allies in Europe and elsewhere to do a better job of coordinating efforts against the scourge of terrorism."

O'Malley: "Our hearts go out to the people of France in this moment of loss...as our hearts go out to them and as our prayers go out to them we must remember this: This is the new face of conflict...in the 21st century, and there is no nation on the planet better able to adapt to this change than our nation....we must anticipate these threats before they happen. This is the new sort of challenge, the new sort of threat that does in fact require new thinking, fresh approaches."

9:00 p.m. Since the first Democratic debate was held one month ago, the field has been cut in half. Former Virginia Sen. Jim Webb, former Rhode Island Gov. and Sen. Lincoln Chafee and Harvard Professor Lawrence Lessig (who didn't even qualify for the last debate) have all dropped out.

That means Saturday night's debate in Des Moines, Iowa features the three remaining candidates: former Secretary of State Hillary Clinton, Sen. Bernie Sanders, I-Vermont, and former Maryland Gov. Martin O'Malley.

CBS News is hosting the debate in conjunction with CBS' Des Moines affiliate, KCCI, and the Des Moines Register. "Face the Nation" anchor John Dickerson will be the principal moderator, and he will be joined by CBS News Congressional Correspondent Nancy Cordes, KCCI anchor Kevin Cooney and the Des Moines Register's political columnist, Kathie Obradovich.

In the aftermath of Friday's attacks in Paris, the debate will focus in part on foreign policy differences among the candidates and strategies to fight extremist groups abroad.

Candidates have already responded, via social media, to the attacks that have left more than 120 people dead and several dozen more injured. While all three have expressed their condolences for the people of Paris, the debate will provide a forum to discuss how the U.S. might prevent such an attack from happening at home.

A CBS News/ New York Times poll released ahead of the debate shows that Clinton enjoys a considerable lead, with support from 52 percent of Democratic primary voters nationally.

CBS News Associate Producer Rebecca Shabad contributed to this story.