Officials later confirmed the message was sent in error. "I asked a managerial type near the lobby where we should go and he said we could all go to the banquet hall he was in". It was unfortunate and regrettable. "This can not happen again".
The message also blared across television sets in the state - where residents have been on edge in recent months amid growing tensions between the Trump administration and North Korea.
Employees undergo a shift change three times a day.
People who say they got through to the office were then told it was a mistake.
The Federal Communications Commission is launching a full investigation into the alert, according to its Chief of Staff Matthew Berry.
"Called 911.Operator said it's a drill of Civil Defense Emergency System but someone pushed the wrong buttons". Efforts to reach Hawaii's Emergency Management Agency were unsuccessful.
Miyagi said there was a "check list" that should have been followed.
"I think it depends on the carrier", he said, "what is the carrier or the company that sponsors that, but we'll review that too, because all of them should have gotten this". It's an matter of executing the process.
But her tweet might not have been sent fast enough, because people were in a state of surprise shortly after the message went through.
The "human error", of course, does not necessarily have to be one in which someone mistakenly sent the alert; the Emergency Management Agency might have received false information, or misinterpreted radar data, or any number of options.
An emergency alert that states "BALLISTIC MISSILE THREAT INBOUND TO HAWAII".
Kim Jong-un has threatened to unleash his country's growing missile weapon capability against the U.S. territory of Guam or USA states, prompting Donald Trump to threaten tough actions against Pyongyang.
It's not clear what caused the error.
It was enough time to send people scrambling for shelter and their cars. I didn't understand that.
The US military has not explained the mistake.
"BALLISTIC MISSILE THREAT INBOUND TO HAWAII", the message read.
"It's totally unacceptable", said U.S. Sen.
"Bottom line is if there's an alert like this that occurs again, take the appropriate action".