HONOLULU (HawaiiNewsNow) - For the first time since the Cold War, an "attack warning" siren with a wailing tone sounded Friday across the state.
The test happened at 11:45 a.m., and will be scheduled for each subsequent first working day of the month.
Residents in some areas said they didn't hear the sirens, and emergency officials were set to follow up on reports of glitches.
"The bottom line on the tone on this ... (it) means something's coming. you need to get inside and stay inside right away," said Vern Miyagi, head of the Hawaii Emergency Management Agency. "You got to take cover. You got to find the best place you can. ... This action will save lives."
In the event of an actual attack, Hawaii would have just 12 to 13 minutes to prepare.
And if there was an actual missile attack from North Korea, the state would trigger the wailing siren after an alert from the U.S. Pacific Command.
Residents said the siren test was something of a wake-up call.
"We need to take this very seriously," said Honolulu resident Preston Jones. "Anything's possible these days and we need to be prepared."
David Pettinger, of Aiea, said the test got him thinking about what he'd do in the event of an actual nuclear attack.
"I would probably just hunker down and stay where I am," he said. "I don't know what more can be done."
Meanwhile, Mililani resident Deborah Sutherlan said the siren test left her feeling a little shaky.
"I was ready for the regular (tsunami) siren and then I said, 'That's different.' It caught my attention,'" Sutherlan said. "
"We've got 14, 20 minutes? I'm going to hug whoever's nearest to me that I love and just try to take cover, and just stay indoors and block everything so that we don't breathe anything that might come our way."
At a news conference earlier this week to discuss the test, Gov. David Ige said it's vital that the public understand that this is the "new normal."
"We believe it is imperative that we be prepared for every disaster in today's world and that includes a nuclear attack," Ige said.
Miyagi said the purpose of the unique attack warning siren — which would be used only in the event of a nuclear attack on Hawaii — is to "provide the people of Hawaii and the visitors with as much warning as possible."
He added, "When people say we shouldn't prepare for this, it's not true. We should prepare for this unlikely, let's emphasize that, unlikely event."
State leaders want people to be prepared to shelter in place for as long as 14 days, depending on the damage and residual radiation.
"The guidance to the schools right now is 48 hours -- 48 hours in place depending on where their location is with respect to the impact area. The 48 hours is based on the decay of radioactivity after the event," Miyagi said.
Officials have also stressed that while it's important to prepare for the threat of a nuclear attack from North Korea, it's also essential to be ready for more likely disasters, including hurricanes and tsunami.
The siren test Friday happened directly after the tsunami warning siren with a steady tone.
And it comes amid rising tensions with North Korea, and as the state tries to better prepare residents for the improbable but not impossible threat of a nuclear attack from the rogue nation.
On Tuesday, North Korea launched its first ballistic missile test in 10 weeks, in a move that could shut the door on a diplomatic resolution.
Seoul's Joint Chiefs of Staff said the U.S. and South Korean militaries were analyzing the launch data from the missile, which was fired from an area in Pyongsong, a city close to North Korea's capital. In response, it said South Korea conducted a "precision-strike" drill, without elaborating.
After the North Korean missile test on Tuesday, President Trump told reporters that the United States will "take care of it," but didn't elaborate.
Trump also said that "it is a situation that we will handle."
A week ago, the Trump administration declared North Korea a state sponsor of terrorism, further straining ties between governments that are still technically at war. Washington also imposed new sanctions on North Korean shipping firms and Chinese trading companies dealing with the North.
North Korea called the terror designation a "serious provocation" that justifies its development of nuclear weapons.