dozens of rounds from an automatic weapon slicing through the air, as country star jason aldeen performed. [ gunfire ] the crowd of 22,000 erupting in panic and screams as they tried to find kover from the hail of bullets. just sounded like fireworks, almost fake at the beginning. once everyone hit the floor, just stayed down and get out as fast as we can. not only it was the sound but the shells that were coming down, bullets coming down on the deck of the stage. and we could actually see them bouncing off the deck of the stage. reporter: the stage and crowd were right on the las vegas strip. several hundred yard frs from t mandalay bay. it was there that a gunman shattered the windows with a hammer-like device and opened fire. the whole convert venue visible from his perch. it was like shooting fish in