At least one person was killed and seven people were missing after a dam broke Tuesday morning on the Hawaiian island of Kauai, sending almost 500 million gallons of water down an island valley.

"Sounded like a 747 jet crashing here in the valley, all the trees popping and snapping and everything," resident John Hawthorne told The Associated Press. "It was just a horrendous sound, and it never quit."

The U.S. Coast Guard is searching the area around Kilauea Bay, on the northern side of the island, with helicopters, boats and airplanes. One body was recovered, according to a statement from the Coast Guard.

The break in the dam on Kilauea Stream was reported about 9:45 a.m. (2:45 p.m. ET), according to Lt. Cmdr. DesaRae Janszen, a spokesman for the Coast Guard.

Kauai was under a flash flood watch because of heavy rain when the dam broke. In the past two days, 2 to 8 inches of rain have fallen across the island, with as much as 17 inches in higher elevations.

Ed Teixeira, state vice director of civil defense, said in Honolulu that officials were worried about more problems as they checked other dams on the island.

"I would characterize this as a growing crisis on Kauai," he told The Associated Press.

Maj. Gen. Robert Lee, director of state civil defense, told The Honolulu Advertiser another dam downstream from the one that broke Tuesday "could go at any time," raising new fears for dazed residents.

The water cut off access to and from thousands of rural houses and luxury condominiums along Kauai's north shore. At least two homes were swept off their foundations and several hundred feet of the island's main highway were washed out.

"I thought ... a tidal wave is coming over the trees," Marie Atkinson, whose house sits near a stream bank in the valley, told The Advertiser.

Ed Doty, who lives near the downstream reservoir that officials feared could be the next to go, told The Advertiser, "The water (going over the reservoir) looked like Niagara Falls. It just gave way. I don't know what we're going to do with this. ... We've got a canyon."

Edwin Matsuda, an engineer who heads the state's safety programs, has said nearly all of Hawaii's dams were built early in the past century before federal standards existed or the advent of the state's program for assessing dam and levee safety.

One resident, Linda Pasadava, president of the Kilauea Neighborhood Association, blamed construction and development in the area for the catastrophe.

"This is what happens when you dig into mountains," Pasadava told The Honolulu Star Bulletin. "The community I've spoken to is furious -- they just don't know who to be furious at."

Others just worried how they would get by while the threat of another break hung over the island.

"We have no bread, we're low on water and rice...," Maria Berdon, a clerk at a supermarket in cut-off Princeville, told The Star Bulletin. "People are just panicked."