President Donald Trump today called the deadly shooting in Las Vegas on Sunday night an "act of pure evil."
"We are joined together today in sadness, shock and grief," Trump said from the White House.
At least 58 people were killed, and hundreds more were wounded when a gunman fired on concertgoers from the nearby Mandalay Bay Resort and Casino. It is the worst mass shooting in modern U.S. history.
Trump said he ordered the White House to lower its flags to half-staff in memory of the victims. He offered condolences to the families of the victims and said he would be praying for a "full and speedy recovery" for the injured.
He thanked the first responders and the officers of the Las Vegas Metropolitan Police Department (LVMPD) for their "miraculous" speed in responding to the scene.
"To have found the shooter so quickly after the first shots were fired is something for which we will always be thankful and grateful," said Trump, who later spoke on the phone with LVMPD Sheriff Joseph Lombardo.
He said he will visit Las Vegas on Wednesday "to meet with law enforcement, first responders and the families of the victims."
"Our unity cannot be shattered by evil. Our bonds cannot be broken by violence. And though we feel such great anger at the senseless murder of our fellow citizens, it is our love that defines us today -- and always will, forever," Trump said.
After his remarks, Trump ignored questions from reporters on whether the shooting was an act of domestic terrorism. But during his meeting with Thailand's Prime Minister Prayut Chan-o-cha in the Oval Office, Trump said today was a "sad day" and a "very, very sad moment for me and for everybody."
The president and first lady Melania Trump, as well as Vice President Mike Pence and his wife, Karen Pence, later led a moment of silence on the White House South Lawn.
Pres. Trump, VP Pence, First Lady, Karen Pence bow their heads and hold a moment of silence for the victims of the Las Vegas shooting. pic.twitter.com/CIxUJwNiK4— ABC News (@ABC) October 2, 2017
Earlier this morning, Trump sent his "condolences and sympathies" to the victims and their families of the shooting.
My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!— Donald J. Trump (@realDonaldTrump) October 2, 2017
House Speaker Paul Ryan ordered the flags that fly over the U.S. Capitol to be lowered to half-staff.
“America woke up this morning to heartbreaking news. This evil tragedy horrifies us all," he said in a statement. "To the people of Las Vegas and to the families of the victims, we are with you during this time. The whole country stands united in our shock, in our condolences and in our prayers."
The Pences said they were praying for the victims and families affected by the "senseless violence."
To victims, families & loved ones affected by this senseless violence in Las Vegas, Karen & I are praying for you & offering our love...— Vice President Pence (@VP) October 2, 2017
...The hearts & prayers of the American people are with you. You have our condolences and sympathies.— Vice President Pence (@VP) October 2, 2017
To the courageous first responders, thank you for your acts of bravery.— Vice President Pence (@VP) October 2, 2017
My heart and prayers goes out to victims, families & loved ones! #PrayForLasVegas— Melania Trump (@FLOTUS) October 2, 2017
1:2 America woke up this morning to the horrific news of a devastating mass shooting in Las Vegas.— Ivanka Trump (@IvankaTrump) October 2, 2017
2:2 Our collective hearts are breaking for the victims and their families. ?? #lasVegas— Ivanka Trump (@IvankaTrump) October 2, 2017
Las Vegas Mayor Carolyn G. Goodman thanked the first responders.
Pray for Las Vegas. Thank you to all our first responders out there now.— Carolyn G. Goodman (@mayoroflasvegas) October 2, 2017
Nevada Rep. Dina Titus said Las Vegas is a "resilient and benevolent town that will not be intimidated by acts of violence."
My full statement on the shooting. pic.twitter.com/BMNQa0R0Be— Dina Titus (@repdinatitus) October 2, 2017
Nevada Gov. Brian Sandoval called the shooting a "tragic and heinous act of violence."
A tragic & heinous act of violence has shaken the #Nevada family. Our prayers are w/ the victims & all affected by this act of cowardice.— Governor Sandoval (@GovSandoval) October 2, 2017
Nevada's two senators — Republican Dean Heller and Democrat Catherine Cortez Masto — said they are continuing to monitor the situation.
Senseless, horrifying act of violence in Las Vegas tonight. Praying for all the victims & those impacted by the tragedy.— Dean Heller (@SenDeanHeller) October 2, 2017
Praying for all those affected by this senseless tragedy. Thank you to all the first responders. I will continue to monitor the situation.— Senator Cortez Masto (@SenCortezMasto) October 2, 2017
House Majority Whip Steve Scalise, R-La., who returned to work but is still recovering after being shot during a congressional baseball practice in June, tweeted that he and his wife are praying for the victims.
Jennifer and I are praying for the victims of this unspeakable violence in Las Vegas.— Rep. Steve Scalise (@SteveScalise) October 2, 2017
Scalise also encouraged others to donate blood as a way to help those injured in the shooting.
"In this tragic moment, I encourage people across America to stand together in solidarity, and to support the Las Vegas community and all of those affected, especially by giving blood and encouraging others to do the same," Scalise said in a statement. "In the face of unspeakable evil, our whole nation must respond with countless acts of kindness, warmth and generosity."
The two Democratic senators from Connecticut, where the Sandy Hook Elementary School shooting took place in 2012, called for action by Congress.
"This must stop," Sen. Chris Murphy, who held an all-night talkathon in June 2016 urging action in Congress on gun control, said in a statement. "The thoughts and prayers of politicians are cruelly hollow if they are paired with continued legislative indifference. It's time for Congress to get off its a-- and do something."
Sen. Richard Blumenthal said in a statement, "It has been barely a year since what was previously the largest mass shooting in American history — the deadly attack at Pulse nightclub. In the interim, thousands more have been lost to the daily, ruthless toll of gun violence. Still, Congress refuses to act. I am more than frustrated, I am furious."
The responses from other members of Congress came pouring in as many woke Monday morning to the tragic news:
Senate Minority Leader Chuck Schumer of New York
Deeply saddened for the people of Las Vegas and the country. We will keep the victims & their families in our hearts.— Chuck Schumer (@SenSchumer) October 2, 2017
House Majority Leader Kevin McCarthy of California
Such a senseless tragedy in Las Vegas. This horrific act has our nation praying for the victims and their families. May God bless us all.— Kevin McCarthy (@GOPLeader) October 2, 2017
House Minority Leader Nancy Pelosi of California
Horrified and heartbroken by the awful tragedy in #LasVegas last night. Praying for those lost, wounded & waiting for news from loved ones.— Nancy Pelosi (@NancyPelosi) October 2, 2017
Sen. Orrin Hatch, R-Utah
Woke up this morning to the horrifying news out of Las Vegas. Shocking and senseless. God bless the victims and their families.— Senator Hatch Office (@senorrinhatch) October 2, 2017
Sen. Cory Booker, D-N.J.
My soul aches over Las Vegas. My prayers are with the victims. And my prayers are with our nation, may we resolve to do more stop such evil.— Cory Booker (@CoryBooker) October 2, 2017
Sen. James Lankford, R-Okla.
Our prayers are with the victims & their families of the despicable act of terror in Las Vegas. This was pure evil.— Sen. James Lankford (@SenatorLankford) October 2, 2017
Rep. Jim Himes, D-Conn.
Once again, I'm devastated by the carnage in NV— Jim Himes (@jahimes) October 2, 2017
Once again, I offer my thoughts & prayers
Once again, I wonder if we'll do anything about it
ABC News' Katherine Faulders, Ali Rogin, Kendall Karson and Rachel Tillman contributed to this report.