Hawaii was plunged into panic on Saturday when an official alert warned people a ballistic missile was about to hit - only for it to turn out to be a false alarm.
Residents in the American state, which has a population of almost 1.5 million, reportedly ran for cover when they spotted the message on their smartphones.
"BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL," the emergency alert read.
Children were seen sheltering in locker rooms while others were witnessed looking “terrified” and crying, according to a congressman for the state.
However it was later discovered that a button had been pressed in “human error” during a change in shifts, wrongly issuing the warning.
The blunder caused further fury after it took 38 minutes to alert people via the same system that the original message was incorrect.
“There is no missile threat or danger to the State or Hawaii. Repeat. False Alarm,” the second message read.
Between the two messages other national bodies and politicians had confirmed it was a blunder and posted messages online announcing the fact.
The incident was so serious that Donald Trump, the US president, was briefed about what had happened. White House spokeswoman Lindsay Walters said it "was purely a state exercise."
HAWAII - THIS IS A FALSE ALARM. THERE IS NO INCOMING MISSILE TO HAWAII. I HAVE CONFIRMED WITH OFFICIALS THERE IS NO INCOMING MISSILE. pic.twitter.com/DxfTXIDOQs— Tulsi Gabbard (@TulsiGabbard) January 13, 2018
Hawaii officials apologised for the mistake and an investigation is now underway to work out exactly what went on.
"I deeply apologise for the trouble and heartbreak that we caused today," said Vern Miyagi, administrator of Hawaii's Emergency Management Agency.
"We've spent the last few months trying to get ahead of this whole threat, so that we could provide as much notification and preparation to the public.
"We made a mistake," he told journalists. "We're going to take processes and study this so that this doesn't happen again.
"The governor has directed that we hold off any more tests until we get this squared away."
The blunder comes at a time of heightened tension between America and North Korea, with the latter testing ballistic missiles over increasingly long distances.
Brian Schatz, the senator for Hawaii, said of the officials: "They blew it here. It was totally unacceptable ... they don't quite understand how bad this was.”
He told CNN: “The fact that the state government knew it was a false alarm but took between 30 and 40 minutes to alert the public is just an abomination."
AGAIN FALSE ALARM. What happened today is totally inexcusable. The whole state was terrified. There needs to be tough and quick accountability and a fixed process.— Brian Schatz (@brianschatz) January 13, 2018
Lauren McGowan, on holiday in Maui with family members and friends, was on her way to breakfast when her phone blared the alert.
She and her family quickly returned to their hotel, where staff ushered them along with some 30 people to a basement cafeteria and distributed water and food.
The alert and rush to shelter caused "confusion," McGowan said, particularly for the children in the group.
"No one had any idea what was really going on," the 28-year-old from New York told AFP, explaining they had no cell service underground.
"It was a bit jarring for sure," she said of the experience.
But McGowan added, "I'm not going to let it ruin the rest of my vacation" and it's "definitely good to know that the system works."
Students at the University of Hawaii campus were filmed running in panic after the smartphone alert was issued.
This was my phone when I woke up just now. I'm in Honolulu, #Hawaii and my family is on the North Shore. They were hiding in the garage. My mom and sister were crying. It was a false alarm, but betting a lot of people are shaken. @KPRC2pic.twitter.com/m6EKxH3QqQ— Sara Donchey (@KPRC2Sara) January 13, 2018
Other Hawaii residents also sent and received text messages from loved ones believing a missile strike was imminent.
My son texted me from Hawaii. It was a simple text. “ I love you” but I knew something was up. I googled #hawaii and almost lost my mind. ��— Orpheus Black (@Orpheus_Black) January 13, 2018
Sara Donchey wrote: “This was my phone when I woke up just now. I'm in Honolulu, #Hawaii and my family is on the North Shore. They were hiding in the garage. My mom and sister were crying. It was a false alarm, but betting a lot of people are shaken.”
“There was an Emergency alert for a missile threat in Hawaii around 8 am Hawaii time. My mom texted me around that same time, "I love you" and it's just now clicking why she randomly sent me that because she thought that was her last moments. I'm sitting at work crying,” posted another user.
Orpheus Black wrote: “My son texted me from Hawaii. It was a simple text. “ I love you” but I knew something was up. I googled #hawaii and almost lost my mind.”