"I'm inside the Mandalay now on the 31st floor - I can hear the automatic fire coming from one floor ahead, one floor above us."
"Be advised it is automatic fire, fully automatic fire from an elevated position, take cover."
"This is correct, it's automatic fire, I'm right below it."
And so the deadliest mass shooting in modern US history unfolded at the Mandalay Bay Resort and Casino in Las Vegas, where gunman Stephen Paddock killed 59 and injured 527 by spraying bullets at a crowd of more than 22,000 attending a country music festival.
By the time swat teams stormed the gunman's hotel room on the 32nd floor, he was already dead surrounded by an arsenal of rifles which officials said had been modified to make them automatic.
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The emergency services audio, provided by Broadcastify.com, captures officers responding to the horrific incident as they try to help the injured and put an end to the situation.
The popping sound of the automatic rifle can chillingly be heard in the background at one point.
Emergency units are advised not to approach from northbound because "he's shooting this way ... it's a horrible cover spot," an officer says.
Another describes how he is dealing with an injured person with "a gunshot wound to the leg," while another at the scene has "a gunshot wound to the mouth".
There is still no known motive for the attack.
The damaged windows on the 32nd floor room that was used by the shooter in the Mandalay Hotel and the Route 91 festival venue (front) after a gunman killed more than 58 people and wounded more than 500 others when he opened fire on a country music festival in Las Vegas, Nevada on October 2, 2017. Mark Ralston / AFP
The scene in front of the stage following a mass shooing at the Route 91 Harvest Country Music Festival on the Las Vegas Strip in Las Vegas, Nevada, US. Mike Blake / Reuters
The damaged windows on the 32nd floor room that was used by the shooter in the Mandalay Hotel after a gunman killed at least 58 people and wounded more than 500 others when he opened fire on a country music concert in Las Vegas, Nevada. Mark Ralston / AFP
Eric Paddock brother of Las Vegas gunman Stephen Paddock, speaks to members of the media outside his home, on Monday, October 2, 2017, in Orlando, Florida. Paddock told the Orlando Sentinel: "We are completely dumbfounded. We can't understand what happened." John Raoux / AP Photo
This home was owned by Stephen Paddock, who opened fire on a crowd at a country music concert on the Las Vegas Strip on Sunday. Scott Sonner / AP Photo
The American flag is at half-staff at the White House in Washington on Monday, October 2, 2017. President Donald Trump ordered that flags be lowered at all government buildings to honour the victims of the mass shooting in Las Vegas. Pablo Martinez Monsivais / AP Photo
The Eiffel tower is seen with its lights turned off in Paris, France, on Monday, October 2, 2017. Paris mayor Anne Hidalgo said the Eiffel tower would turn off its lights Monday at midnight Paris hour to pay tribute to Las Vegas and Marseille victims. Kamil Zihnioglu / AP Photo
The Guns & Guitars store in Mesquite, Nevada. The store's general manager Christopher Sullivan said in a statement that Stephen Paddock showed no signs of being unfit to buy guns. Paddock killed dozens and injured hundreds Sunday night when he opened fired at an outdoor country music festival in Las Vegas. Chris Carlson / AP Photo
The Empire State Building lights, normally lit in colours, are dimmed on Monday, October 2, 2017, in New York, in sympathy for the victims of the mass shooting in Las Vegas. Kathy Willens / AP Photo
A message on the video board reads 'Pray For Las Vegas' during a moment of silence before the Washington Redskins game against the Kansas City Chiefs at their Monday Night NFL football game at Arrowhead Stadium in Kansas City, Missouri. Larry Smith / EPA
Police form a perimeter around the road leading to the Mandalay Hotel (background) after a gunman killed at least 50 people and wounded more than 400 others when he opened fire on a country music concert in Las Vegas, Nevada on October 2, 2017. Mark Ralston / AFP
Police return to their vehicles after patrolling around the Mandalay Hotel where a gunman killed at least 50 people and wounded more than 200 others when he opened fire on a country music concert in Las Vegas, Nevada on October 2, 2017. Mark Ralston / AFP
Two festivalgoers leave the area around the Mandalay Hotel. Mark Ralston / AFP
Police personnel stand outside the home of Stephen Paddock on Monday, October 2, 2017, in Mesquite. Police identified Paddock as the gunman at a music festival on Sunday evening. Mesquite Police via AP
A sign warns motorists heading toward Las Vegas that part of the Vegas Strip is closed, on October 2, 2017. Robyn Beck / AFP
This undated photo provided by Eric Paddock shows his brother, Las Vegas gunman Stephen Paddock. Stephen Paddock opened fire on the Route 91 Harvest Festival on Sunday, October 1, 2017, killing dozens and wounding hundreds. Courtesy of Eric Paddock via AP
This 1979 photo shows Benjamin Hoskins Paddock, the father of Stephen Paddock, the gunman who killed dozens of people and injured hundreds at a music festival in Las Vegas. The elder Paddock, who went by the name Bruce Ericksen during his time in Lane County, Oregon. He had escaped from a federal prison in Texas in 1969, following a conviction for a string of bank robberies in Arizona. Charlie Nye/The Register-Guard via AP
Police block the street near the scene of a mass shooting at the Route 91 Harvest festival on Las Vegas Boulevard in Las Vegas, Nevada. Paul Buck / EPA
Mourners react during a candlelight vigil at the University of Nevada Las Vegas (UNLV) for victims of the mass shooting in Las Vegas. Eugene Garcia / EPA
Benjamin Hoskins Paddock, father of Stephen Paddock. The FBI wanted poster stated that Paddock's father was a serial bank robber who was 'diagnosed as psychopathic' and spent eight years on the FBI Most Wanted list after escaping prison. EPA/FBI
Student mourners console each other during a candlelight vigil at the University of Nevada Las Vegas (UNLV) for victims of the mass shooting in Las Vegas. Eugene Garcia / EPA
Updated: October 03, 2017, 2:08 PM