The shooter, identified by police as 64-year-old Stephen Paddock, began shooting at concert goers from the 32nd floor of the Mandalay Bay Resort and Casino, which is near the outdoor concert space on the Las Vegas Strip. Police later confirmed that Paddock was found dead in his hotel room.
Many world leaders and other notable figures took to social media to express their sorrow and send sympathy to the victims and their families. Here is what they said:
President Trump and U.S. politicians reactions to the shooting
U.S. President Donald Trump tweeted Monday morning that his "warmest condolences and sympathies" were with the victims and their families.
Former presidential candidate Hillary Clinton described the shooting as a "cold-blooded massacre." She went on the criticize the National Rifle Association (NRA).
Former President Barack Obama wrote that he and Michelle Obama were praying for the victims.
World leaders' reactions to the Las Vegas shooting
Other world leaders echoed Trump's sentiments. Prime Minister Mark Rutte of the Netherlands tweeted that his thoughts were with "all the victims of this atrocity," while Lars Løkke Rasmussen, Prime Minister of Denmark, wrote: "Horrified by the brutal shootings in Las Vegas. My condolences and deepest sympathy to the victims, the wounded and their loved ones."
A telegram sent on behalf of Pope Francis said the pontiff was sending " the assurance of his spiritual closeness to all those affected by this senseless tragedy." Pope Francis commended " the efforts of the police and emergency service personnel," and offered "the promise of his prayers for the injured and for all who have died, entrusting them to the merciful love of Almighty God."
British Prime Minister Theresa May said her thoughts were "with the victims and emergency services" and Jeremy Corbyn, leader of the opposition, posted a similar message.
Bana Alabed, the young Syrian refugee who became known all over the world for live-tweeting the war from Aleppo, wrote that she was praying for Las Vegas. Her mother, Fatemah, added: "Nothing is worth killing for."
Celebrity reactions to the Las Vegas shooting
Country music singer Jason Aldean was performing when Paddock opened fire at the Las Vegas concert. Video footage shows Aldean running from the stage as gunshots ring out. "Tonight has been beyond horrific," he wrote in an Instagram post early Monday morning. "I still don't know what to say but wanted to let everyone know that me and my crew are safe. My thoughts and prayers go out to everyone involved tonight."
Many celebrities also shared their thoughts on the "devastating" tragedy.
This is a developing news story and will be updated.