At 1:26am ET, Twitter user Stefinatrix wrote: "I'm on the 6th floor [of the Mandalay Bay]. Shots reported on floor 29 now. Listening to LVPD scanner feed. Security guard shot on 32nd floor."
Warning: offensive language
She also said that the gunman was firing on police cars from the 32nd floor earlier, according to LVPD scanners.
Landon Jensen tweeted: "We are safe. Multiple patients down. Automatic gun fire. Possibly multi suspects."
Twitter user Fitz wrote: "Friend working event said it happened during Jason Aldean's set, dozens of shots fired (automatic?) #MandalayBay #Route91 #activeshooter"
Musician Luke Combs was at the music festival. He tweeted: "Active shooter at @Route91Harvest in Vegas. We're safe. Love you guys," he wrote.
Country singer Jake Owen, who appeared to be in Mandalay Bay, tweeted: "Gun shots!!! Vegas. Pray to god. Love you guys. Love you Pearl."
Professional poker player Dan Bilzerian, who was at the event, streamed footage of himself running. Noises that could be helicopters or gunfire could be heard in the background.
"Holy f**k this girl just got shot in the f**king head," he said, "This is so f**king crazy."
The LVMPD tweeted: "Please avoid heading to the south end of the Strip. Las Vegas Blvd is shut down at Tropicana, southbound past Russell Rd at this time."
Dozens were seen on aerial footage fleeing the Mandalay Bay, which was locked down, as police surrounded the location.
According to Twitter users listening in on police scanners, police breached a room on the 32nd floor of the Mandalay Bay hotel; shortly afterward, the suspect's body was found.
A concert-goer says he heard what sounded like fireworks while he was watching Jason Aldean's performance at the Route 91 Harvest country music festival Sunday night.
Thirty-six-year-old Kodiak Yazzi said the music stopped temporarily and started up again before another round of pops sent the performers ducking for cover and fleeing the stage.
As the 40,000 fans in the crowd began to flee, Yazzi took cover and said he saw flashes of light coming from the Mandalay Bay hotel tower high above.
The bursts of pops would start and stop for more than five minutes. He says he saw dozens of ambulances as he ran for safety. He later got a Lyft driver to take him home to suburban Henderson.Las Vegas police say one suspect is 'down.'
