NBC News' live blog tracked the ups, downs and confrontations of the fourth Democratic primary debate of the 2020 presidential election cycle, co-hosted by CNN and The New York Times.
The largest group of candidates took the stage Tuesday night at Otterbein University in Westerville, Ohio. They included front-runners Joe Biden and Sen. Elizabeth Warren; Sen. Bernie Sanders, who returned to the campaign after having a heart attack two weeks ago; billionaire activist Tom Steyer, who appeared in his first debate of the cycle; and Hawaii Rep. Tulsi Gabbard, who missed the September go-round after failing to qualify.
For full politics coverage, download the NBC News app.
Fact check: How many assault rifles are in circulation?
"Five million assault weapons are on the streets of America today — during the course of this debate eight people will die from gun violence," Harris said.
It’s hard to know exactly how many assault-type rifles are in circulation, but there's some evidence there are far more than 5 million of those weapons on the street. Some estimates go as high as 10 million to 16 million.
Meanwhile, 100 people are killed with guns each day, according to gun control advocates, a number that includes suicides. That’s roughly four an hour, and the debate is scheduled to be three, not two, hours.
Police shootings are a leading cause of death for young black men
When asked about mandatory gun buybacks tonight, Harris said gun violence was the leading cause of death of young black men.
According to research published in July in the Proceedings of the National Academy of Sciences, police shootings claim the lives of an average of about 1,000 people each year in the United States, and have become a leading cause of death for young men.
The study did not differentiate between killings later determined to be justified and those that were not. The study did find that the risk is particularly acute for young black men and those between the ages of 20 and 35. However, over the course of a lifetime, about one in 1,000 black men “can expect to be killed by police,” according to the study.
Police shootings account for nearly 2 percent of all deaths of black men between the ages of 20 and 24, compared to just 0.5 percent of deaths among young white men in the same age range. And a 40-year-old black man lives with about the same risk of being shot and killed by police as a 20-year-old white man in the United States.
These figures together help to make homicide the seventh leading cause of death for all black Americans in 2017, according to the Centers for Disease Control and Prevention.
Alta Vista for life
Yang when asked about breaking up the big tech companies drops a bit of a burn on Bing, Microsoft’s search engine.
"There’s a reason why no one is using Bing today," he said. "I’m sorry Microsoft, it’s true."
Warren’s got a (fitness) plan
Biden flips the script on age: 'With it comes wisdom'
Biden would be the oldest person elected president, but when pressed about his age, instead of being defensive, he said it would be an asset.
“Because I’ve watched it, I know what the job is and I’ve been engaged,” the former vice president said. “I’m running because of my age.”
He said that his age comes with decades of legislative experience and the ability to command respect on the international stage. Biden said he would release his health records before the first primary vote, but questions regarding age are not likely to die down, especially as health concerns are on voters’ minds.
Widespread support for some gun control measures
Democrats are right that a majority of Americans support universal background checks, an assault weapons ban and a voluntary gun buyback program.
According to an August NBC/WSJ poll, 89 percent of Americans back universal background checks, while 75 percent support voluntary buybacks. Sixty-two percent back an assault weapons ban.
But there are some measures that Americans say go too far.
The same poll found that just 25 percent back a ban on handguns.
Bernie addresses recent heart attack
Tuesday’s debate marked a return to the campaign trail for Sanders, who had a heart attack earlier this month. When asked about his health, Sanders said he was “healthy” and “feeling great,” and invited viewers to come to an upcoming rally in Queens, pledging a vigorous campaign moving forward. He thanked colleagues and supporters for well-wishes.
Do gun safety groups want mandatory buybacks? They’re split.
Beto O’Rourke accused Pete Buttigieg of disrespecting March for Our Lives, the activist group founded in the wake of the Parkland shooting, by calling mandatory buybacks a “shiny object” that distracts from other policies.
“That was a slap in the face to every single one of those groups and every single survivor of a mass casualty assault with a AR-14 and AK-47,” he said. “We must buy them back.”
O’Rourke is right that March for Our Lives backs mandatory buybacks, but major gun safety groups mostly oppose the approach or have minimized it. Giffords, another gun safety group, put out a polling memo for candidates warning that the issue “could be dangerous” when trying to win over voters who support other gun restrictions.
Giffords favors an alternate approach, which Warren mentioned: Requiring owners of existing assault weapons to register their weapons and accept new restrictions on their possession and sale, similar to automatic weapons.
“I want to use the method we used for example with machine guns,” Warren said. “We registered them, we put in a huge penalty if you didn’t register them, and a huge tax on them, and we let people turn them in.”
Castro gets applause for answer on tackling gun deaths
Castro was the first candidate to mention the Texas shooting in which a white police officer shot and killed a black woman, Atatiana Jefferson.
He got big applause for mentioning police shootings as gun violence and talking about growing up in Texas against the backdrop of gun violence.
"Police violence is also gun violence and we need to address that," he said.
Castro said he is against mandatory and voluntary gun buybacks but he did not directly address how he plans to stop violence committed by handguns versus assault weapons.
Jefferson, meanwhile, was like a disproportionate share of those who die in police shootings each year, black and unarmed.
Prior to Tuesday’s debate, Castro, a Texas native, Warren,Booker, Harris, Sanders, O’Rourke, Steyer and Yang all posted public statements on Twitter expressing outrage, sympathy for Jefferson’s family or calls for investigation and reform.
On Tuesday night, only Castro mentioned Jefferson by name.
Read NBC News' report on how the shooting — coming on the heels of the sentencing of a former Dallas police officer in the killing of her neighbor, Botham Jean — is fueling tensions with police in Forth Worth.