Multiple law enforcement agencies responded to an active shooter situation at a Walmart in El Paso, Texas, on Saturday where at least 20 people were killed, according to local and national media reports.

Texas Gov. Greg Abbott (R) said that 20 people were confirmed killed, and 26 more were injured in the shooting, according to Fox News and NBC News.

One person was taken into custody, police said, adding that they did not believe there were other suspects at the scene or elsewhere. The suspect was said to be a 18-year-old man. A manifesto obtained by The Hill reportedly posted online by the shooter was filled with racist and hate-filled speech about the rate of immigration in America and Texas in particular, and linked such issues to elites in both the Democratic Party and GOP.

UPDATE: One person is in custody in connection with the El Paso, Texas shooting, El Paso police confirm. "We don't believe there is anybody outstanding, so we are starting to secure the scene." https://t.co/mPi7INB5mS pic.twitter.com/CtOJXmiatm — ABC News (@ABC) August 3, 2019

The city's mayor had previously told CNN that multiple suspects were in custody.

El Paso police and Dallas's branch of the Bureau of Alcohol, Tobacco, Firearms and Explosives responded to the scene, which was reportedly next to the city's Cielo Vista Mall.

BREAKING: ATF is en route to assist @EPPOLICE at the scene of a reported shooting in the area of #CieloVistaMall in #ElPaso TX. Please stay away from the area and refrain from posting first responder activity on social media. https://t.co/uw3DEFZRJt pic.twitter.com/0KqUK5nmmI — ATF Dallas (@ATFDallas) August 3, 2019

The El Paso Police Department tweeted after the shooting began that reports of multiple shooters were coming in and urged bystanders to avoid the area. The department did not immediately return a request for more details from The Hill but put out a call for blood donations on Twitter.

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"Blood needed urgently. Multiple injured transported to various hospitals. Blood donation centers Vitalent Blood Services at 424 s Mesa Hills and 133 N Zaragoza," the department tweeted.

Scene is still Active. We have multi reports of multiple shooters. Please avoid area police conducting search of a very large area. Media staging will be given when area is secure. — EL PASO POLICE DEPT (@EPPOLICE) August 3, 2019

Blood needed urgently. Multiple injured transported to various hospitals. Blood donation centers Vitalent Blood Services at 424 s Mesa Hills and 133 N Zaragoza — EL PASO POLICE DEPT (@EPPOLICE) August 3, 2019

Mark Lambie, a photojournalist at the El Paso Times, tweeted a video of medical response teams at the scene of the shooting.

Huge medical response to active shooter at Walmart Cielo Vista. @elpasotimes pic.twitter.com/9O4M9uDYdu — mark lambie (@LambieMark) August 3, 2019

Former Rep. Beto O'Rourke Beto O'RourkeJimmy Carter says his son smoked pot with Willie Nelson on White House roof O'Rourke endorses Kennedy for Senate: 'A champion for the values we're most proud of' 2020 Democrats do convention Zoom call MORE (D-Texas), who previously served as the city's mayor and is currently running for president, tweeted his response to the "heartbreaking" tragedy as it was unfolding. At a press conference Saturday afternoon, he pledged to return to the city while it deals with the tragedy.

.@BetoORourke delivers emotional statement about shooting in El Paso, Texas, he says he will cut short his campaign trip in Nevada and head to Texas immediately. pic.twitter.com/sPESbpb3tz — Ben Pu (@BenPu_nbc) August 3, 2019

"Truly heartbreaking. Stay safe, El Paso. Please follow all directions of emergency personnel as we continue to get more updates," he tweeted.

Truly heartbreaking. Stay safe, El Paso. Please follow all directions of emergency personnel as we continue to get more updates. https://t.co/BU0AH6Y8Rv — Beto O'Rourke (@BetoORourke) August 3, 2019

The White House released a statement Saturday afternoon that said President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE was monitoring the situation.

"The President continues to receive updates from his national security team on the tragic shootings in El Paso. Federal Government personnel, including the FBI and ATF, are on the ground in El Paso actively assisting local authorities, who are leading the response to the shootings. The President has pledged the full support of the Federal Government to Governor Abbott," a White House deputy press secretary said.

In a tweet, Trump called the shooting "terrible" and pledged the federal government's support to El Paso's city officials.

"Terrible shootings in ElPaso, Texas. Reports are very bad, many killed. Working with State and Local authorities, and Law Enforcement. Spoke to Governor to pledge total support of Federal Government. God be with you all!" he tweeted.

Terrible shootings in ElPaso, Texas. Reports are very bad, many killed. Working with State and Local authorities, and Law Enforcement. Spoke to Governor to pledge total support of Federal Government. God be with you all! — Donald J. Trump (@realDonaldTrump) August 3, 2019

Attorney General William Barr Bill BarrHillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Bipartisan representatives demand answers on expired surveillance programs YouTube to battle mail-in voting misinformation with info panel on videos MORE released a statement slightly later through the Justice Department, writing that the agency "joins in mourning" with the people of El Paso.

“The Justice Department joins in mourning with the people of El Paso, Texas. Those who commit such atrocities should be held accountable swiftly and to the fullest extent the law allows," he vowed.

Abbott, in a statement, thanked first responders at the scene and vowed that Texans would "unite in support of all the victims."

"Now in the beautiful city of El Paso. Texans grieve today for the people of this wonderful place. We unite in support of all the victims. We thank First Responders for their swift action. We ask God to bind up the wounds of all who’ve been harmed," he tweeted.

Now in the beautiful city of El Paso.



Texans grieve today for the people of this wonderful place.



We unite in support of all the victims.



We thank First Responders for their swift action.



We ask God to bind up the wounds of all who’ve been harmed. pic.twitter.com/2l8jDPHbe1 — Greg Abbott (@GregAbbott_TX) August 3, 2019

Walmart also released a statement following the shooting, tweeting that the company was "in shock" over the events in El Paso.

"We're in shock over the tragic events at Cielo Vista Mall in El Paso, where store 2201 & club 6502 are located. We’re praying for the victims, the community & our associates, as well as the first responders. We’re working closely with law enforcement & will update as appropriate," Walmart tweeted.