Eight people were killed and five were listed as missing after flash floods struck a town in the western state of Utah overnight, state officials said early Tuesday.

A wall of water hit people in two vehicles in Hildale, washing the automobiles and their 16 passengers downstream, Washington County Emergency Services said in a statement posted on Facebook.

Only three people in the vehicles made it out safely and among those dead and missing were children, including a four-year-old, Hildale assistant fire chief Kevin Barlow told The Salt Lake Tribune.

"They were well back from the flood, but this was a very significant surprise flash flood that caught them unawares," Barlow said, adding that the passengers seemed to be from various families.

The flooding followed heavy rains that began late Monday afternoon and left multiple homes without power and water.

Early Tuesday, the Utah Division of Emergency Management confirmed that "an additional victim has been located below the Central Street crossing bringing the total number of confirmed fatalities to eight. There are still five unaccounted for."

Crews searched for missing people in the flood waters but scaled back the operation at nightfall as conditions were still dangerous.

Flooding left streets clogged with mud, rocks and debris, Washington County Emergency Services said in a statement posted on Facebook.

The flooding reportedly began after heavy rain hit canyons just north of town.

One resident of Colorado City, just across the border in Arizona, told NBC news that the rain marked one of the worst storms he had seen in decades, lasting for only 20 or 30 minutes.

"Everyone is family here, and it's a tragedy however you look at it," the resident, Ted Barlow said.

US Senator John McCain of Arizona said his thoughts were with those affected by the storm.

"My deepest condolences are with the victims and loved ones of those killed in flash flooding along the Arizona-Utah border last night," he said in a statement, thanking law enforcement and search-and-rescue crews for their quick action.

The National Weather Service earlier in the day had issued a flash flood warning, prompting nearby Zion National Park to close its narrow slot canyons, the Weather Channel reported.

Scattered thunderstorms could appear in the Hildale area Tuesday afternoon, according to weather.com.

Hildale is located around 300 miles (500 kilometers) south of Salt Lake City.

The town was the home base for Warren Jeffs, the self-declared "Prophet" who was jailed for life after being found guilty in 2011 of child sexual assault.

He is the former president of the Fundamentalist Church of Jesus Christ of Latter-day Saints (FLDS), which split from the mainstream Mormon Church of Jesus Christ of Latter-day Saints (LDS) in the early 20th century.

The town's population includes a mix of Jeffs' loyalists and defectors, according to NBC.