It then said, "This is not a drill", before advising people indoors to stay indoors and people outside to seek immediate shelter.
Rep. Tulsi Gabbard, D-HI, confirmed the false alarm on Twitter 12 minutes after the errant message was sent.
There is no yet word on where the alert originated from.
The alert turned out to be false and the result of human error.
Correction messages were later sent out to mobile phones in Hawaii and were broadcast on television via a scrolling red banner that read in part, "There is no missile threat or danger to the State of Hawaii".
Officials quickly confirmed afterward that the alert was a false alarm and had been sent out by mistake.
In November, Hawaii said it would resume monthly statewide testing of Cold War-era nuclear attack warning sirens for the first time in at least a quarter of a century, in preparation for a possible missile strike from North Korea, state officials said at the time.
The alert moved in all capital letters on social media at 8:07 a.m. local time and was sent to cellphones.More news: Wrong woman killed in love triangle murder-for-hire plot, officials say
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CNN was told by a viewer in Hawaii that both the initial threat warning and the message of false alarm more than 30 minutes later came across the TV warning notification system. "There needs to be tough and quick accountability and a fixed process", he wrote.
"There is no missile threat", Lt. Commander Joe Nawrocki said. "There is nothing more important to Hawaii than professionalizing and fool-proofing this process".
He continued: "Why does it take 38 minutes for us to get a false alarm notice?"
The U.S. Federal Communications Commission announced that it was initiating a full probe into the incident.
North Korean President Kim Jong-un has threatened to unleash his country's growing missile weapon capability against USA states or the U.S. territory of Guam, prompting President Donald Trump to threaten tough actions against Pyongyang.
Hawaii is on the flight path between North Korea and the US.
After the alert was declared an error, many decried the fact that such an incredible error was allowed to happen.