People in Hawaii woke up Saturday to emergency alerts sent to their mobile phones and broadcast on radio and TV warning of an imminent ballistic missile attack.
The alert turned out to be false and the result of human error.
But for the more than 30 minutes it took before a corrected message was broadcast, the alert caused panic around the state.
Sen. Brian Schatz of Hawaii wrote on Twitter that "the whole state was terrified."
The false emergency alert apparently happened because "the wrong button was pushed," Hawaii House Speaker Scott Saiki said in a statement.
"This system we have been told to rely upon failed and failed miserably today," Saiki said. "I am deeply troubled by this misstep that could have had dire consequences."
He added, "Apparently, the wrong button was pushed and it took over 30 minutes for a correction to be announced. Parents and children panicked during those 30 minutes."
The emergency alert was sent to people's mobile phones in Hawaii starting at about 8:07 a.m. local time with the startling words all in caps, "Ballistic missile threat inbound to Hawaii. Seek immediate shelter. This is not a drill."
Shortly after, a spokesman for the U.S. Pacific Command, Dave Benham, told ABC News in a statement that no ballistic missile threat to Hawaii was detected.
"Earlier message was sent in error. State of Hawaii will send out a correction message as soon as possible," Benham said.
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."
Many people did not receive a corrected alert on their phones until 8:45 a.m., 38 minutes after the warning of the incoming missile.
The chairman of the Federal Communications Commission meanwhile tweeted that the FCC is launching an investigation into how the false emergency alert was sent.
Gov. David Ige said at a press conference Saturday afternoon that the error happened during a routine procedure that occurs as workers are changing shifts.
"An error was made in emergency management which allowed this false alarm to be sent," Ige said. "It was a procedure that occurs at the change of shift, enabling [us] to make sure that the system is working, and an employee pushed the wrong button."
The governor added that in order to prevent the error from occurring again the state will change its procedures by having more than one person involved in pushing the correct button.
Diane Cluxton, who lives on the Big Island, said she was grocery shopping with her husband when she received the false alert this morning.
"My husband got it at the same time and then all of a sudden you heard all these "What?" throughout the store, because everybody was receiving it all at the same time," Cluxton told ABC News. "One person actually sought shelter in a doorway waiting for some other notification, so it definitely looked like everybody received the alert."
Cluxton said some people in the store eventually received a second alert on their phone saying it was a false alarm.
ABC News' Kateri Jochum contributed to this report.
This is a breaking news story. Check back for updates.