What started as a country music concert turned into a bloody massacre Sunday night, and it's now being called the worst mass shooting in U.S. history.
The shooting happened just after 10 p.m. as 22,000 people gathered to watch country music artist Jason Aldean perform for the Route 91 Harvest Festival concert in the streets outside the Mandalay Bay Casino.
At least 59 people were killed, and Las Vegas police report more than 527 people were injured and taken to area hospitals.
The gunman has been identified as 64-year-old Stephen Craig Paddock, a retiree with no criminal history, from Mesquite, Nevada. Police say he had as many as 23 guns with him, and he was killed during a confrontation as police raced to confront him on the 32nd floor of that casino. Authorities say the gunman attached what is called a "bump-stock" to two of his weapons, in effect converting semiautomatic firearms into fully automatic ones.
Sheriff Joseph Lombardo said authorities found 19 more guns, explosives and thousands of rounds of ammunition at Paddock's home. Also, several pounds of ammonium nitrate, a fertilizer that has been used to make explosives, were found in his car, the sheriff said.
ISIS claimed responsibility for the attack, saying Paddock had converted to Islam, but the Islamic terrorist group provided no evidence and officials say they have not discovered any ties.
Witnesses on the ground described the shooting as a chaotic scene of screaming and weeping with blood everywhere.
"My friend was like 'I just got hit,'" one witness said. "He got hit three times and people started diving for the ground and it just continued, it was chaotic."
Footage from the scene shows people falling over each other to get away.
Not easy to watch but have to commend the courage of the people dealing with this situation in Las Vegas. pic.twitter.com/3vGY0cIXdy
— Fl Bass Adventures (@FlBassAdventure) October 2, 2017
In other videos from the concert, many concertgoers aren't even aware a shooting is taking place as the "pop-pop-pop-pop" of the gun can be heard in the distance. Some say they thought it was fireworks.
"We refused to believe it was a shooting until it kept going and going and then Jason Aldean left the stage and then everyone started fleeing," one witness said.
Absolute chaos in Las Vegas. Mass Shooter fires into crowd murdering at least two ppl and injuring several more. pic.twitter.com/ko37DuBodV
— The Columbia Bugle (@ColumbiaBugle) October 2, 2017
Concertgoers used their personal vehicles to try and get shooting victims to the hospital.
People helping to load up and transport Las Vegas shooting victims to the hospital pic.twitter.com/l4hqQoSLMK
— INDI Realty Fin Biz (@BizIndi) October 2, 2017
SWAT teams were sent to the resort, clearing out the 29th floor and working their way up.
"Through investigation and response we determined there was a shooter on the 32nd floor of the Mandalay Bay. Officers responded to that location and engaged the suspect at that location," police say.
Click play to hear police dispatchers as they hunt down the shooter.
Police say they have tracked down a person they were looking for, Marilou Danley, who lived with the suspect. They say she is out of the country at this time.
White House Press Secretary Sarah Sanders issued a statement saying, “The President has been briefed on the horrific tragedy in Las Vegas. We are monitoring the situation closely and offer our full support to state and local officials. All of those affected are in our thoughts and prayers.”
President Trump tweeted about the shooting saying, "My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you."
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
Off-duty police officers who were at the concert are among the dead. Two more officers were also hurt.
An ISIS propaganda video targeting Las Vegas was released in May – but as the investigation began, police said they didn't believe this was an act of terrorism. Still, no one could say what was behind this deadly mass shooting.