The entire state of Hawaii was under a flash flood watch Tuesday morning after heavy rain overflowed a dam and forced people to evacuate their homes for fear of fast-rising waters and landslides.
"Deep moisture will remain over the state through tonight," the National Weather Service in Honolulu warned early Tuesday.
The grounds were already saturated from heavy rainfall Monday that caused the Kaupakalua Dam on the island of Maui to overflow. The weather service said Tuesday that the dam could fail.
Maui officials, who had thought Monday that the dam had failed, said later that it had not suffered structural damage. Still, those in Haiku near the Kaupakalua Dam and Kaupakalua Road were ordered to evacuate, according to Facebook posts on the Maui County page.
Water levels were above normal, about 3 feet below the top of the dam, a post on the county's page said at about 8:30 a.m. local time Tuesday.
The dam can hold 68 million gallons of water, NBC affiliate KHNL reported.
Nearby residents were told not to return. "People near heavily flowing streams also should evacuate or seek higher ground," the Maui County posts said. "Even if it appears that there is less rainfall and conditions are improving, people should not return to the area until there is an 'all clear' announcement."
One evacuation shelter remained open Tuesday morning.
Officials said floodwaters destroyed Peahi Bridge and heavily damaged the Kaupakalua Bridge in Haiku. At least six homes were heavily damaged or destroyed.
The Maui Fire Department reported responding to more than a dozen calls from residents who were trapped by rising waters.
"This has been unprecedented flooding, and we will be making damage assessments today," Maui County Mayor Michael Victorino said. "I ask everyone to stay vigilant and be safe."
While some roads that had been closed Monday have reopened, others remain shuttered, Maui police said. And an early morning power outage affected more than 1,300 customers.
"This is a real flooding situation we have not seen in a long time," Victorino said Monday during a live address on Facebook. "Some of the residents have told me this is the worst they've seen in over 25 years."
"If you have family and friends and you can get out of the area, that is probably preferable. But be careful if you see high water. Turn around and go back," Victorino said. "Do not try to cross it at this time."
The National Weather Service cautioned residents to expect mudslides in steep terrain.
A dam failure turned fatal in Hawaii in 2006, when seven people were killed after the Ka Loko dam on the island of Kauai collapsed.
But East Maui residents say they haven't seen rains like Monday's downpours in years.
"I have lived here for 30 years, and I think this is the first time that I have seen so much rain," Makawao resident Lydia Toccafondi Panzik told KHNL. "I've seen hurricane times, I've seen floodings, but this was really a bad one."