A preliminary federal investigation released last month said the recorded drill message began and ended with the phrase “exercise, exercise, excise.” It also included language scripted for use during an actual missile alert: “This is not a drill.”

But the emergency worker, who has been fired, claims he “didn’t hear ‘exercise’ at all in that whole transmission.” As soon as he realized his error, he “just wanted to crawl under a rock.”

“It was incredibly difficult for me, very emotional,” he said, adding that his team was immediately flooded with phone calls from frantic citizens.