LAS VEGAS (AP) — The rapid-fire popping sounded like firecrackers at first, so many in the crowd of 22,000 country music fans didn’t understand what was happening when the band stopped playing and singer Jason Aldean bolted off the stage.

“That’s gunshots,” a man could be heard saying emphatically on a cellphone video in the nearly half-minute of silence and confusion that followed. A woman pleaded with others: “Get down! Get down! Stay down!”

Then the bang-bang-bang sounds resumed. And pure terror set in.