Twelve people, including a 10-year-old boy, are dead after flash floods tore through the town of Hildale, Utah, Monday night, on the border with Arizona, authorities said.
One person is missing, Washington County Emergency Services said this afternoon.
Separately, four people were killed in nearby Zion National Park and three people remained missing as a result of the flooding.
"I join with other Utahns in mourning today the lives lost in two tragic incidents at Zion National Park and Hildale," Gov. Gary R. Herbert said a statement. "Jeanette and I send our thoughts and prayers to the families and friends of those who have lost loved ones."
The victims in Hildale had stopped their cars at a point where waters from Maxwell Canyon cross Central Street, authorities said.
They exited their cars, then got back in, when a massive flash flood swept them away, authorities in Colorado City, Arizona, said at a news conference today. Hildale serves as a sister town of Colorado City.
The 10-year-old's body was found over 6 miles downstream from the incident, authorities said.
The flash flooding left streets littered with mud, sand, boulders and debris.
Damaged homes and power outages were also reported, according to Washington County Emergency Services Public Information Officer Pete Kuhlmann.