On Saturday morning, just after 8 a.m. local time, a Hawaii state employee hit the wrong button on a computer during a shift change and accidentally sent an alert to many of the state’s cellphones that a ballistic missile was about to strike. For nearly 40 minutes, scores of Hawaii residents thought their world was about to end.

“BALLISTIC MISSILE THREAT INBOUND TO HAWAII,” the alert said, in all-caps, to the island chain of about 1.4 million people. “SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL.”

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