Democratic candidates call for gun control in wake of El Paso, Dayton shootings The candidates all quickly commented on the attack from the campaign trail.

Two shootings that killed 20 people at a Walmart in El Paso, Texas, on Saturday, and nine people in Dayton, Ohio, in the early hours of Sunday morning brought immediate reactions from the crowded field of Democratic presidential candidates on the campaign trail.

Calls for a period of reflection before discussing politics, a familiar refrain for years in the wake of mass shootings, ceded to calls for increased gun control before all of the details of the attacks were known.

Sunday

"El Paso is a community that shows up for one another—on our best days and our worst," former Rep. Beto O'Rourke, who calls El Paso home, tweeted Sunday. "I met Rosemary's family on the plane back to El Paso. They asked that we visit her and share her story. She was shot in the chest but is doing well after surgery. She's strong—just like our city."

O'Rourke cancelled an appearance at California's San Quentin State Prison and returned to El Paso Saturday evening, where he visited University Medical Center.

"It's incredibly heartbreaking to see what these families are going through right now," the Texan said on a Sunday appearance on ABC News' "This Week."

O'Rourke in front of reporters Sunday also called for laws that make it harder for people to get a gun who he said "should not have one in the first place," along with universal background checks, closing all the loopholes and ending the sales of assault weapons and weapons of war.

"We also have to acknowledge that that the open racism and intolerance and hatred that we are seeing throughout this country Being being echoed and trafficked in by the President of the United States who encourages this kind of hatred," he said.

Former Housing and Urban Development Secretary Julián Castro, also of Texas, similarly called out President Donald Trump in a "This Week" appearance Sunday, saying that "division and bigotry and fanning the flames of hate has been [Trump's] political strategy."

In a statement Sunday after both shootings, Ohio Rep. Tim Ryan said, "I'm calling in Congress to immediately end its August recess and reconvene in Washington to take up a package of legislation meant to stop these acts of horror and other acts of gun violence that affect every single American."

Sen. Elizabeth Warren tweeted, "We're waking up to the second mass shooting in as many days. I'm heartsick for the 29 people killed this weekend in El Paso and Dayton—and all the other lives we lose every day due to senseless gun violence. We need to take urgent action to end the gun violence epidemic."

Sen. Kamala Harris also took to Twitter Sunday morning, saying, "We cannot remain idle and allow this level of carnage to ravage our communities. We need courage. We need to act."

Saturday

On Saturday, many of the 2020 presidential candidates -- 19 of 24 -- were in Las Vegas for the AFSCME Convention as news of the El Paso shooting started to spread in the media.

"We are in this unimaginably just distraught moment in this country, where we seem to be almost accepting this idea that these are going to be a regular occurrence," Sen. Cory Booker, D-N.J., told reporters a the AFSCME forum. "And so I have had enough of this, especially living in a community where gunshots are all too regular."

"We have to in this election, we have to have leaders are willing to stand up and say, I'm not going to let this issue be be determined by what the interests of the corporate gun lobby are," he added.

New York Mayor Bill de Blasio hinted at a similar reluctance of conservative politicians to stand up to the gun lobby, and the face of gun rights, the National Rifle Association.

"Countless tragedies all because the gun lobby has certain 'leaders' more scared of losing support than losing loved ones," he said Saturday on Twitter. "Enough empty words. These families deserve action."

South Bend, Indiana, Mayor Pete Buttigieg focused his comments at the forum on gun control and the growing threat of white nationalism. The suspect in the El Paso shooting expressed a desire to kill as many Mexicans as possible after being arrested, two law enforcement officials told ABC News.

"America is under attack from homegrown white nationalist terrorism," Buttigieg said. "And we have to talk and act about two things in this country. First of all, we are the only country in the world with more guns than we have people. We can respect the Second Amendment and not allow it to be a death sentence for thousands of Americans, and two, white nationalism is evil."

Several candidates were critical of Trump for not doing more to create real gun reform in the U.S.

"Well, his responsibility is to do what the American people are would like him to do, and that is to support the common sense gun safety legislation, that the overwhelming majority the American people support," Sen. Bernie Sanders, I-Vt., said. "That's not hard."

Former Maryland Rep. John Delaney said "a lot can be done through executive action" in response to increasing gun protections.

Joe Biden, one of the president's most persistent targets of criticism, said he'd reached out to O'Rourke about the shooting and challenged the NRA's honesty.

"Folks, even the NRA members know better," Biden said late Friday, before the shootings. "Even the NRA members know we need universal background checks, the majority of them."

"This is not just about what policy works better," Sen. Amy Klobuchar, D-Minn., said. "This is about a power of an outside group, and people who are too afraid to act. And it's not just about mass shootings, it's about every single day in America, in neighborhoods across the country."

"My heart goes out to the families and individuals impacted by the El Paso shooting," Andrew Yang wrote on Twitter on Saturday. "We owe them and all Americans common sense gun safety laws. Other societies respond to senseless tragedies -- we must do the same. We are better than this."

"We haven't been able to put an end to these horrific shootings," said John Hickenlooper, who was governor of Colorado during the mass shooting at a movie theater in Aurora. "This should make every American furious."

"We can start with requiring universal background checks and licensing and limiting high-capacity magazines," he continued. "No one should be cowed by the NRA ever again."

Trump responded to the tragedies via Twitter, saying Saturday, "Today's shooting in El Paso, Texas, was not only tragic, it was an act of cowardice. I know that I stand with everyone in this Country to condemn today's hateful act. There are no reasons or excuses that will ever justify killing innocent people."

"God bless the people of El Paso Texas. God bless the people of Dayton, Ohio," Trump added on Twitter on Sunday.

ABC News' Jeff Cook, Zohreen Shah, Sasha Pezenik, Molly Nagle, Cheyenne Haslett, Matthew Vann and Alexandra Svokos contributed to this report.