A false alarm has put the people of Hawaii through a terrifying ordeal.
A ballistic missile was heading their way, according to an urgent message sent to their mobile phones on Saturday morning local time.
TV and radio also carried the warning.
North Korea however hadn't fired anything. It was a case of human error by local emergency officials.
"It was a procedure that occurs at the change of shift where they go through to make sure that the system is working and an employee pushed the wrong button," explained Hawaii Governor David Ige.
He said he was "angry and disappointed" over the incident, which he described as "totally unacceptable".
The mistaken alert stated: "EMERGENCY ALERT BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL."
Sent to mobile phones and aired on television and radio shortly after 8 a.m. local time on Saturday, it was issued amid high international tensions over North Korea's development of ballistic nuclear weapons.
Stacey Bow, 56, of Honolulu, said she received the emergency alert on her smart phone. She awakened her 16-year-old daughter with the news. "She became hysterical, crying, you know, just lost it," she said.
Told to seek immediate shelter and that it wasn't a drill, tourists also panicked.
"When we got the alarm, we were actually terrrified," said one holidaymaker.
"We were on the 36th floor of our hotel. We didn't know what to do. We were kind of frantic. We got our shoes on. We were about to come downstairs when the lobby told us to stay indoors. We are still nervous. We were on the 36th floor!"
It wasn't until almost 40 minutes later that a correction cancelling the false alarm was sent to mobile phones. Authorities have pledged a full investigation to ensure such an incident never happens again.
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.
North Korean President Kim Jong-un has threatened to unleash his country's growing missile weapon capability against the US territory of Guam or US states, prompting President Donald Trump to threaten tough action against Pyongyang, including "fire and fury".
Briefed by aides, Trump was wrapping up a round of golf at Trump International Golf Club in West Palm Beach, Florida when the incident was unfolding.