WASHINGTON — The Hawaii employee who sent out a false alarm earlier this month warning of an incoming missile attack said he misheard a message played during a drill and believed a ballistic missile was actually heading for the state, according to a federal investigation.

This contradicts the explanations previously offered by Hawaii officials, who have said the Jan. 13 alert was sent because the employee hit the wrong button on a drop-down menu.

The cellphone alert sent to Hawaii residents set off a wave of panic across the state, coming as heightened tension with North Korea has fueled fears of nuclear attacks on the United States. To make matters worse, the alarming message blaring “BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL.” went uncorrected for an agonizing 38 minutes.

Authorities were apologetic after what Gov. David Ige, D, called “a terrifying day when our worst nightmares appeared to become a reality.”

The Federal Communications Commission said in a preliminary report released Tuesday that the state employee who sent out the alert “claimed to believe … that this was a real emergency, not a drill.” Wireless emergency alerts warning of danger are typically sent out by state and local officials through a partnership between the FCC, the Federal Emergency Management Agency and the wireless industry.

The incident began when a night-shift supervisor decided to test incoming day-shift workers with a spontaneous drill, the FCC report stated. The supervisor managing the day-shift workers appeared to be aware of the upcoming test but believed it was aimed at the outgoing night-shift workers. As a result, the day-shift manager was not prepared to supervise the morning test, the FCC said.

Following standard procedures, the night-shift supervisor posing as U.S. Pacific Command played a recorded message to the emergency workers warning them of the fake threat.