Sirens echoed loud and clear in O'ahu ahead of Hurricane Lane, the major storm that is forcing Hawaii officials to go all out trying to warn residents.
Residents in Hawaii have recently faced devastating volcanic eruptions and earthquakes, but it's the first time in decades that a Category 3 cyclone has come this close to the islands.
With nearly 300,000 tourists in the state and many residents who have never lived through a hurricane, authorities are not waiting until the last minute to get the word out.
On Thursday, the shrill sound of emergency sirens rang for three minutes. It was the latest attempt by authorities to encourage people to evacuate from areas prone to flooding.
"This is being done now so that anyone who wants to get to a shelter can do so safely while there is still daylight," Honolulu county and city officials said in a news release.
It was also a reminder that several shelters are open on the island, officials said.
In a news conference, Honolulu Mayor Kirk Caldwell said authorities were taking "so much precaution" because of the potential life-threatening impacts of Lane.
"We don't want people after the fact saying, 'why didn't you alert us, why didn't you alert us?'"
Caldwell said the county is working to get ahead of the storm, which is expected to bring tropical storm-force winds and heavy rain Thursday and Friday.
Torrential rains from the storm already have triggered landslides and caused flooding on other islands.
Fire engines and other emergency vehicles also blasted an emergency message using their speakers.
"A hurricane warning is in effect. Extremely dangerous wind and flooding may occur tonight. Flooding may occur in coastal areas, near streams, and low lying areas. If your home is threatened, leave the area," a portion of the message said.
There are more than 170 outdoor warning sirens in O'ahu, CNN affiliate KGMB reported, but the alarm is inaudible in parts of the island.
A massive text warning was also sent to mobile phones.
"Extremely dangerous winds and flooding possible, leave the area if threatened," the message said.
The alarm and emergency messages were sent only to people in O'ahu. The system used Thursday was operated locally but it was installed by the Hawaii Emergency Management Agency. Earlier this year, the same agency was under investigation after an employee sent a false ballistic missile alert statewide.
In a tweet, Gov. David Ige said all the mayors in Hawaii are free to decide whether they want to use the outdoor siren warning system.
And the siren alarm can mean something different in each county, he added.
In the eastern town of Kailua, Nathan Pablo said the sirens took on a new meaning on Thursday.
"Emergency sirens here in Kailua. Heard them all my life when they were tested every month, never heard them used for real," he wrote in a video post on Facebook.