At no time, officials said, was there any indication that a nuclear attack had been launched on the United States. The Federal Communications Commission announced that it had begun “a full investigation into the FALSE missile alert in Hawaii.”
The alert went out at about 8:10 a.m., lighting up phones of people still in bed, having coffee by the beach at a Waikiki resort, or up for an early surf. “BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL,” it read.
Hawaii has been on high emotional alert — it began staging monthly air-raid drills, complete with sirens, in December — since President Trump and Kim Jong-un, the leader of North Korea, began exchanging nuclear threats. Estimates vary, but it would take a little more than half an hour for a missile launched from North Korea to reach Hawaii, traversing an arc of roughly 5,700 miles. State officials said that residents here would have as little as 12 minutes to find shelter once an alert was issued.
Within moments of the first announcement, people flocked to shelters, crowding highways in scenes of terror and helplessness. Emergency sirens wailed in parts of the state, adding to the panic.
“I was running through all the scenarios in my head, but there was nowhere to go, nowhere to pull over to,” said Mike Staskow, a retired military captain.
Allyson Niven, who lives in Kailua-Kona, said her first instinct was to gather her family as she contemplated what she thought would be her final minutes alive.
“We fully felt like we were about to die,” she said. “I drove to try to get to my kids even though I knew I probably wouldn’t make it, and I fully was visualizing what was happening while I was on the road. It was awful.”
Ray Gerst was vacationing on Oahu with his wife to celebrate their 28th wedding anniversary. He received the alert as they pulled up for their tour of Kualoa Ranch.
“All the buses stopped, and people came running out of the ranch and said, ‘Just sit still for a minute, nobody get off the bus, nobody get off the bus,’” he said.
They were taken into the mountains, Mr. Gerst said, and dropped off at a concrete bunker. They sheltered in place for about 15 minutes, he said, during which time they had no cell signal.
“It was scary,” Mr. Gerst said. “I mean, there was no intel.”
At Konawaena High School on the Island of Hawaii, where a high school wrestling championship was taking place, school officials, more accustomed to alerts of high surf or tsunamis, moved people to the center of the gym as they tried to figure out how to take shelter from a missile.
“Everyone cooperated,” said Kellye Krug, the athletic director at the school. “Once they were gathered, we let them use cellphones to reach loved ones. There were a couple kids who were emotional, the coaches were right there to console kids. After the retraction was issued, we gave kids time to reach out again.”
Matt LoPresti, a state representative, told CNN that he and his family headed for a bathroom. “I was sitting in the bathtub with my children, saying our prayers,” he said.
Natalie Haena, 38, of Honolulu, said she was getting ready to take her daughter to ice skating lessons when the alert came. “There’s nothing to prep for a missile coming in,” she said. “We have no bomb shelters or anything like that. There’s nowhere to go.”
In Washington, Lindsay Walters, a deputy press secretary, said that President Trump had been informed of the events. “The president has been briefed on the state of Hawaii’s emergency management exercise,” she said. “This was purely a state exercise.”
Senator Brian Schatz of Hawaii said the mistake was “totally inexcusable.”
“The whole state was terrified,” he said. “There needs to be tough and quick accountability and a fixed process.”
While the cellphone alerting system is in state authorities’ hands, the detection of missile launches is the responsibility of the United States Strategic Command and Northern Command. It was the military — not Hawaiian officials — that was the first to declare there was no evidence of a missile launch.
The false alert was a stark reminder of what happens when the old realities of the nuclear age collide with the speed — and the potential for error — inherent in the internet age. The alert came at one of the worst possible moments — when tension with North Korea has been at one of the highest points in decades, and when Mr. Kim’s government has promised more missile tests and threatened an atmospheric nuclear test.
During the Cold War there were many false alarms. William J. Perry, the defense secretary during the Clinton administration, recalled in his memoir, “My Journey at the Nuclear Brink,” a moment in 1979 when, as an under secretary of defense, he was awakened by a watch officer who reported that his computer system was showing 200 intercontinental ballistic missiles headed to the United States. “For one heart-stopping second I thought my worst nuclear nightmare had come true,” Mr. Perry wrote.
It turned out that a training tape had been mistakenly inserted into an early-warning system computer. No one woke up the president. But Mr. Perry went on to speculate what might have happened if such a warning had come “during the Cuban Missile Crisis or a Mideast war?”
The United States faces an especially difficult problem today, not just because of tense relations with North Korea but also because of growing fears inside the military about the cyber vulnerability of the nuclear warning system and nuclear control systems.
Because of its location, Hawaii — more than any other part of the United States — has been threatened by escalating tensions and the risks of war, and preparations have already begun there.
On Friday, the day before the erroneous alert, several hundred people attended an event in Honolulu sponsored by the Chamber of Commerce in which military commanders, politicians and others discussed the threat to the islands’ population.
“The U.S. is the designated recipient — and that’s because we are public enemy No. 1 to North Korea,” Dan Leaf, a retired Air Force lieutenant general and Pacific Command deputy commander, was quoted as saying in The Honolulu Star Advertiser.
The Hawaii Emergency Management Agency has been holding “are you ready” drills. As a chain of islands, Hawaii is subject to all kinds of threats — hurricanes, volcanoes, earthquakes and tsunamis — but officials have made clear that none is more urgent now than the threat of an attack by North Korea, given how little time there would be between an alert and the detonation of a bomb.
The fifth page of an emergency preparation pamphlet issued by the Hawaii Emergency Management Agency features a picture of a rocket lifting off: “Nuclear Threat — Unlikely But Cannot Ignore It.”
Vern T. Miyagi, the administrator of the agency, said that during the drill, an employee — whom he did not identify — mistakenly pushed a button on a computer screen to send out the alert, rather than one marked to test it. He said the employee answered “yes” when asked by the system if he was sure he wanted to send the message.
Mr. Miyagi, going through a detailed timeline of the events at an afternoon news conference, said the agency tried to correct the error on social media. It took 38 minutes to send out a follow-up message canceling the original alert, which he acknowledged was a shortcoming with the alert system that the agency would fix.
Mr. Rapoza said he did not know if anyone would be disciplined for the mistake. “At this point, our major concern is to make sure we do what we need to do to reassure the public,” he said. “This is not a time for pointing fingers.”
The panic that followed the alert — if relatively short-lived — gripped the islands. There were reports of people seeking shelter by parking their cars inside a highway tunnel that cuts through a mountain. When the announcement was rescinded, a digital highway sign read: “Missile alert in error: There is no threat.”
People in Hawaii tend to know what to do to protect themselves to threats of a tsunami or a hurricane. The prospect of nuclear annihilation was entirely new terrain.
“So this was the most terrifying few minutes of my LIFE!” Paul Wilson, a professor at Brigham Young University-Hawaii, said on Twitter. “I just want to know why it took 38 minutes to announce it was a mistake?!?”
Chris Tacker, a veteran who lives in Kealakekua, said the mistake had left her angry and frustrated.
“I didn’t know where to go,” she said. “Anyone try to dig a hole in lava? Good luck trying to build a shelter. I’m stocking my liquor cabinet.”
Still, she added, “If we don’t have our sense of humor about this, it’s all over.”
An earlier version of this article misspelled the surname of a retired Air Force lieutenant general quoted in the Honolulu Star Advertiser. The general’s name is Dan Leaf, not Leak.