The massacre in El Paso, Texas, on Saturday that killed 20 people and injured 26 has prompted calls for prayer, expressions of grief — and demands by some Democrats for gun reform.

"This attack is a tragic reminder of our government’s failure to do its most basic duty: to protect American lives. We need gun reform now,” Democratic presidential candidate and former San Antonio Mayor Julián Castro said in a statement.

Castro's sentiments were echoed by several other candidates who urged the United States to confront what they portrayed as a gun violence epidemic.

President Donald Trump pledged the full support of the federal government to El Paso and Texas, and tweeted "God be with you all!"

....Melania and I send our heartfelt thoughts and prayers to the great people of Texas. — Donald J. Trump (@realDonaldTrump) August 4, 2019

Vice President Mike Pence said in a statement that his thoughts and prayers are with the victims and the entire community.

"Saddened by the loss of so many innocent lives in El Paso, TX,” Pence said. “Our prayers are with the victims, their families, and the entire community. Grateful for the courageous efforts and swift action by federal law enforcement and local first responders."

A suspect is in custody and multiple law enforcement sources identified him as Patrick Crusius, 21, a resident of the Dallas area. Police said he was reportedly armed with a rifle.

Texas Gov. Greg Abbott said in a statement that "El Paso was struck by a heinous and senseless act of violence." A day of what should have been leisurely shopping "turned into one of the most deadly days in the history of Texas."

"Our hearts go out to the victims of this horrific shooting and to the entire community in this time of loss," he said in the statement on behalf of his wife and himself. "While no words can provide the solace needed for those impacted by this event, I ask that all Texans join Cecilia and me in offering our prayers for the victims and their families."

Democratic presidential candidate Beto O'Rourke, a former congressman from El Paso, said he was "devastated" by the shooting, adding, "Our commitment is with those who will change this country so that this doesn't happen again."

Other Democratic presidential hopefuls also weighed in.

Sen. Bernie Sanders, I-Vt., said on MSNBC that "one is speechless."

"What can you say about somebody walking in to, I guess it was a mall, and shooting down, killing 18 people, wounding other people?" Sanders said. "Happens time after time after time after time — I think all over the world, people are wondering about the mental health of the United States of America."

Sanders called for what he described as commonsense gun safety legislation, including universal and expanded background checks and closing the so-called gun show loophole. "For 30 years, I have believed that we need to ban assault weapons."

Former Vice President Joe Biden said in a statement that he was "heartbroken," and asked, "How many lives must be cut short? How many communities must be torn apart? It’s past time we take action and end our gun violence epidemic."

Sen. Cory Booker, D-N.J., said on MSNBC that "there are no words" to express the sorrow and pain felt all over the country over the shooting.

"But that's not enough," he said. "It is not enough. This is a uniquely American problem. No other nation sees this kind of carnage happening within its own borders — unless, of course, they're at war, using weapons of war. We have the power ... to do something about this, and we're not doing it."

Sen. Kamala Harris, D-Calif., referring to both last weekend's deadly shooting at the Gilroy Garlic Festival in California and Saturday's attack in El Paso, tweeted: "My prayers are yet again with families who are grieving and my thanks are with the first responders, but that is not enough. We must act."

Pete Buttigieg, mayor of South Bend, Indiana, tweeted: "How many more must grieve before we act?"

Sen. Elizabeth Warren, D-Mass., called the news out of El Paso "devastating" and said, "We must act now to end our country's gun violence epidemic."

The Rev. Al Sharpton, who has a show on MSNBC, criticized responses that only called for prayer.

"Prayer without works is a dead thing,” Sharpton, citing the Bible, said. "People have been too content to say, 'Let's pray for the families, pray for the injured, pray for our first responders.'"

"We cannot continue being so removed from this and saying, 'OK, I said a prayer for everybody and that’s the length and width of my responsibility,'" he said.