(CNN) An emergency missile alert accidentally went out to everyone in Hawaii on Saturday after an employee "pushed the wrong button."

How did it happen? Hawaii's Emergency Management Agency provided a bit more detail Sunday on what went wrong.

The mishap took place during a routine drill run after a shift change, Vern Miyagi, the agency's administrator, said.

During the drill, an officer in the emergency operation center mistakenly selected an incorrect "template," which shows what message is going to be sent, Miyagi said.

The template that the officer inadvertently selected was prepared to send the message to the public. The officer was supposed to have chosen a template that would only be sent internally.

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