Country singer Jason Aldean was midway through performing a song when gunfire rang out through the Route 91 Harvest country music festival.
Within seconds it was clear that something was very, very wrong - and audience-filmed footage shows Aldean fleeing the stage.
In the wake of America's deadliest mass shooting, Aldean has been subject to trolling by some on social media who've criticised him a for rushing off the stage without warning fans of impending danger.
"Jason Aldean ran off the stage not saying 1 words to the crowd to get out, like a coward ... really love the country eh?" @commanderinfunk wrote, one of many tweets criticising the singer's actions.
In the hours after the shooting, Aldean posted a short message to Instagram describing the shooting as "beyond horrific" and offering his "thoughts and prayers" to the victims.
In a follow-up, Aldean offered an apology - and a call for unity.
"Over the last 24 hrs I have gone through lots of emotions. Scared, Anger, Heartache, Compassion and many others. I truly don't understand why a person would want to take the life of another. Something has changed in this country and in this world lately that is scary to see. The world is becoming the kind of place I am afraid to raise my children in. At the end of the day we aren't Democrats or Republicans, Whites or Blacks, Men or Women. We are all humans and we are all Americans and it's time to start acting like it and stand together as ONE!" he writes.
"That is the only way we will ever get this country to be better than it has ever been, but we have to start now. My heart aches for the victims and their families for this senseless act. I am so sorry for the hurt and pain everyone is feeling right now and there are no words I can say to take that pain away. Just know u all are in my heart and my prayers as we all go through this together. Time to come together and stop the hate!"
Another of the performers on the bill at the festival, country guitarist Caleb Keeter, issued a remarkable open letter after surviving the shooting. A lifelong advocate for the right to bear arms, Keeter said his harrowing night in Las Vegas had completely changed his mind, and delivered an urgent plea for tougher gun laws in the US.