We are going to T next O that horrificio released just a short Tim ag for the first time, we hear fro Americans trapped in that relentless gre in L Vegas, diving for cover. Love ones standing in front of their friends, girlfriends, bonds to sold them along with the audio tonight,s new surveillanc video from a hotel rooftop. The calls reveal, they pleas for help and theatre W nowhere to hide. Back on case to ABC's ie correspon Matt Gutman. Rorter: Tonight, for the first timewe are hearing the unimagin horrors a sniper, perched in a las Vegas window, gunned down unsuspectingconcertgoers in ber. Oh, my god. They're still shooting. You hear shots? Oh, my god.oh, my god. Oh, my god. And your friend has been shot? Oh, MD. Reporter: 911 operators often hearing nothing but screams. Maf the callers bareble to speak. Hello? I don't know where you are. Aldean concert. God Help. The whole concerts dead on thground! Rep the chaos erupting in the heart of the Vegas strip, as country M star jadean was on stage. The tie drowning out his voice. Oh, my god. Oh, od. Oh, my god. Reporter: And there on the 32 floor of the mandalay bay tel was 64-year-old Stephen paddock. Active shooter in room 32135. 32135. Rorter: He turned his room into an arsenal. The helpless binding cover wherever they could. Those 911 calls are department as investigators are still tr to piece together what led paddock to murder 58 people and injure hundreds more in the worst mass sin in mn story. So hard for all the Fies to relive this with this audio tonight. Matt Gutman with us live. And 're learn this evening, tt, that T 911 calls ultimately helped lead police to th gunman? Reporter: That's right, david.they tell us that police and law 32nd floor of THA hot WITN minutes of the oo and it only took another few M minutes for S.W.A.T. Teams to begin T assemble there on the 32 floor. But they wouldn't learn that step paddock had died of a self-infli gunshot wnd for another hour or so when finally breached the door to his room. David? Matt GU, whoasn following this from the start. To that