Hawaii is currently suffering its worst flooding in more than 20 years, with people in the hardest-hit areas being urged to "LEAVE NOW" by officials.
One of the largest dams on the Oahu island is at "risk of imminent failure", warned the island’s emergency team on social media.
"We’ve got a little over 4,000 people directly within the dam evacuation area," said Molly Pierce, a spokesperson for the Oahu Department of Emergency Management, according to Sky’s partner newsroom NBC.
"It could fail," Ms Pierce said of the 120-year-old Wahiawa dam.
The team also warned the only remaining access road out of the nearby town of Waialua is at "high risk of failure".
"Residents in the Waialua area are strongly urged to LEAVE NOW. The remaining access road out of Waialua is at high risk of failure if rainfall continues," posted the Emergency Management team on X on Saturday afternoon UK time.
More than 5,500 people north of Honolulu are under evacuation orders because of the historic weather.
The situation was made worse by a storm last week, which had already left the ground saturated and susceptible to flooding.
Hawaii Governor Josh Green said the cost of the storm could reach $1bn (around £750m), with airports, schools, roads, homes and a hospital all damaged.
"This is going to have a very serious consequence for us as a state," Mr Green said.
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With the exception of emergency workers, Hawaii’s state employees have been sent home to "allow families to focus on getting to safety," he told reporters.
"With catastrophic flash flooding already impacting parts of Oahu, including evacuation orders on the North Shore and the potential for dam-related impacts, we are taking this situation extremely seriously."
Oahu’s North Shore is famous for its big-wave surfing but the area was submerged in vast stretches of muddy floodwater, as the floods lifted homes and cars.
On social media, local residents were organising clean-up parties and rescue attempts, with one man filming as he tried to rescue a neighbour's cat from the muddy waters.
"Mahalo for your service to the community," replied one Instagram user.
(c) Sky News 2026: Hawaii suffers worst flooding in 20 years as residents told to 'LEAVE NOW'
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