Muddy floodwaters from severe rains inundated streets, pushed homes off their foundations, swallowed vehicles and prompted evacuation orders for thousands of residents in towns north of Honolulu on Friday as officials warned of the possible failure of a 120-year-old dam.

Emergency sirens blared along Oahu’s North Shore, where rising waters damaged homes in a community world-renowned for its surfing. Honolulu officials told residents Friday morning to leave the area downstream of Wahiawa dam — long known to be vulnerable — saying it was “at risk of imminent failure.”

Hawaii Gov. Josh Green said at a news conference that there were no fatalities and no unaccounted individuals as of Friday night. 

Honolulu Mayor Rick Blangiardi said 233 people have been rescued so far.

Crew searched by air and by water for people who had been stranded — efforts that were hampered by people flying personal drones to get images of the flooding, said Ian Scheuring, a spokesperson for Honolulu.

Dozens — if not hundreds — of homes had been damaged but officials have not been able to fully assess the destruction, Blangiardi said in an afternoon news conference. Some 5,500 people were under evacuation orders.

“There’s no question that the damage done thus far has been catastrophic,” he said.  

Earlier, Green said this is the largest flood that Hawaii has seen in 20 years and that the flooding will have “very serious consequences for us as a state.”

“The reality is that this storm could cost over a billion dollars of damage in both the private and public sector,” Green said.

Blangiardi said officials felt confident in the stability of the dams on the island, but that it was hard to predict how much rain would come and what it might do.

The National Guard and Honolulu Fire Department airlifted 72 children and adults who had been attending a spring break youth camp at a retreat on Oahu’s west coast called Our Lady of Kea’au, according to city and camp officials. The camp is on high ground but authorities didn’t want to leave them there, the mayor said.

Kimberly R.Y. Vierra, a spokesperson for St. Francis Healthcare System of Hawai’i, which owns the retreat property in west Oahu, said floodwaters had cut off the entrance road to the camp.

On Maui, officials issued an evacuation advisory for some Lahaina neighborhoods after nearby retention basins neared capacity. Parts of those neighborhoods were burned by the massive wildfire that destroyed much of Lahaina in 2023.

Most of the state was under a flood watch, with Haleiwa and Waialua in northern Oahu under a flash flood warning, according to the National Weather Service.  

Green said in a social media post that the Hawaii National Guard has been activated to respond to the flooding. 

“The storm of course is very severe right now, particularly on the northern part of Oahu,” he said, describing chest-high flood waters. “It’s going to be a very touch-and-go day.”

Green told reporters there had been some rescues “directly from rooftops.” He added that “all resources have been mobilized,” to assist residents during the flooding. 

Green said several pet-friendly shelters are open, including ones at Waialua High and Intermediate, Wahiawā District Park, Nānākuli High and Intermediate, and Kahuku Elementary.

Officials have been watching dam levels since a storm last week dumped heavy rain across the state, which led to catastrophic flooding that washed away roads and homes. After the worst of it, a similar but weaker storm was forecast to bring more rain through this weekend.

As she prepared to evacuate to a friend’s home on higher ground, Waialua resident Kathleen Pahinui told The Associated Press in a phone interview that the aging dam is a concern every time it rains.

“Just pray for us,” she said. “We understand there’s more rain coming.”

Officials issued a warning for the dam during heavy rain last week, but the water level receded as the rain subsided.

“The water is actively running over the spillway right now,” she said.

The state regulates 132 dams across Hawaii, most of them built as part of irrigation systems for the sugar cane industry, according to a 2019 infrastructure report by the American Society of Civil Engineers.

Severe flooding in 2021 may have caused a breach of Kaupakalua Dam in the Maui community of Haiku. Several years earlier, in 2018, flooding decimated Hawaii’s taro crop. In 2006, seven people were killed when the Ka Loko dam on the island of Kauai collapsed and water rushed downhill.