Residents and visitors in Hawaii were thrown into a panic on Saturday by a false missile alarm, with many saying they thought they were going to die.
The alert of an incoming ballistic missile was sent wrongly on Saturday morning by an emergency system worker.
Victims of the ordeal spoke of hysteria and panicked evacuations.
Vacationer Jocelyn Azbell had just woken up in her Maui hotel when she was hurried into the hotel's basement to take shelter from an incoming ballistic missile.
"You're thinking, 'Oh my gosh, are we going to die? Is it really a missile (headed) our way, or is it just a test?" the 24-year-old told CNN. "We really didn't know."
Azbell, her boyfriend and hundreds of other hotel guests were "herded like cows" into the basement by staff. "People are crying and people obviously were super scared," she said.
The human error turned the island paradise upside down. People crawled under tables in cafes, were ushered into military hangars and huddled around televisions to watch the news for the latest developments.
"It was a mistake made during a standard procedure at the changeover of a shift, and an employee pushed the wrong button," said Hawaii Governor David Ige.
Hassan Deen, a student at Hawaii Pacific University, told the BBC the alert sparked a frenzy, and he was locked for 47 minutes with 29 other students in a room with rubbish bins.
Emma Hine, who is visiting Hawaii from the UK, told the BBC, "It was one of the worst experiences because I actually thought we were going to die... everyone was genuinely terrified."
Her son, Lewis, a disability campaigner, suffered a seizure due to stress.
Marathon runner Lucja Leonard said she had heard of children being "pushed into drainpipes to get them protected".
The false alarm sparked recriminations, with state officials apologising and President Donald Trump's response called into question - he was reportedly playing golf when the incident occurred.
It was a mistake by an employee at Hawaii's Emergency Management Agency (EMA) who "pushed the wrong button" during procedures that occur during the handover of a shift.
The message was reportedly sent despite an onscreen prompt requesting confirmation.
Mobile phone users received the message at 08:07 (18:07 GMT): "Ballistic missile threat inbound to Hawaii. Seek immediate shelter. This is not a drill."
The alert was corrected by email 18 minutes later but there was no follow-up mobile text for 38 minutes, the Honolulu Star-Advertiser reports.
The alert system is in place because of the potential proximity of Hawaii to North Korean missiles.
A federal investigation has started in the state and officials said they would work to ensure such a false alarm never happened again.
State lawmakers are going to hold a hearing next Friday.