What to Know
At least 59 people were killed and more than 400 sent to hospitals in what would be the deadliest mass shooting in modern US history
The gunman has been identified as Stephen Paddock, of Mesquite, Nevada; he was found dead in his 32nd floor room in the Mandalay Bay hotel
Tens of thousands ran for their lives, screaming, as gunfire erupted; it was believed to have been a "lone wolf" attack, authorities said
President Donald Trump called Sunday's mass shooting at an outdoor music festival in Las Vegas "an act of pure evil" in an address to the nation Monday.
Stephen Craig Paddock opened fire from a high perch late Sunday, leaving at least 59 people dead and more than 500 wounded. It's the deadliest mass shooting in modern American history.
Trump responded from the White House, thanking first responders for what they did to save lives and offering prayers for the victims and their families.
"We pray for the entire nation to find unity and peace, and we pray for the day when evil is banished and the innocent are safe from hatred and from fear," Trump said.
He also said he would visit Las Vegas on Wednesday, and ordered flags across the nation to be flown at half-staff.
Trump also observed a moment of silence Monday afternoon on the south end of the White House lawn.
A bell tolled three times as a solemn Trump, flanked by first lady Melania Trump, Vice President Mike Pence and his wife, Karen, paused on the South Lawn for a moment of silence in honor of the shooting victims.
Flags over the U.S. Capitol were ordered to be lowered to half-staff Monday, House Speak Paul Ryan said.
"This evil tragedy horrifies us all. To the people of Las Vegas and to the families of the victims, we are with you during this time," Ryan said in a statement.
The gunman, who took aim at the crowd as country music star Jason Aldean was performing, was killed on the the 32nd floor of a casino on the Las Vegas Strip. He was identified as 64-year-old Stephen Paddock of Mesquite, Nevada.
Clark County Sheriff Joseph Lombardo said it was believed to be a "lone wolf" attack.
Asked if Trump wants to use the shooting to launch into a policy discussion about gun control, White House press secretary Sarah Huckabee Sanders said now is not the time to discuss policy.
"There’s a time and place for a political debate," she said at a White House press briefing Monday afternoon. "Now is the time to unite as a country. There’s currently an open and ongoing law enforcement investigation; a motive has yet to be determined. It would be premature for us to discuss policy when we don’t fully know all the facts or what took place last night."
Pence also tweeted in response to the shooting, saying, "To victims, families & loved ones affected by this senseless violence in Las Vegas, Karen & I are praying for you & offering our love. The hearts & prayers of the American people are with you. You have our condolences and sympathies."
Pence also thanked the "courageous first responders" for their "acts of bravery."
In Connecticut, officials who have been fighting for stricter gun control laws in the years since the tragic shooting at Sandy Hook Elementary School are calling for action on gun control following the shooting.
"Not again," U.S. Sen. Chris Murphy tweeted, saying his heart is with Las Vegas and he is sending prayers to the victims.
"Nowhere but America do horrific large-scale mass shootings happen with this degree of regularity," Murphy said in a statement. "Last night's massacre may go down as the deadliest in our nation's history, but already this year there have been more mass shootings than days in the year. ... It's time for Congress to get off its ass and do something."
Other politicians from Nevada and around the country responded as well, including former President Barack Obama and Hillary Clinton.
Former Rep. Gabrielle Giffords, saying she knows the "horror" of gun violence all too well, implored lawmakers on Monday to take action following the deadly mass shooting in Las Vegas.
"I know this feeling of heartbreak and horror too well," Giffords, who was gravely wounded in an assassination attempt six years ago in Arizona, said in a statement.
"The massacre in Las Vegas is a grave tragedy for our nation. This must stop — we must stop this."