Last Updated Sep 16, 2015 3:43 AM EDT
SALT LAKE CITY -- A wall of water swept away two vehicles carrying women and children in a Utah-Arizona border town Monday, killing at least 12 people. At least one other is still missing in a community that served as a home base for polygamous sect leader Warren Jeffs, authorities said.
Three people survived as the flash flooding washed the vehicles several hundred yards downstream about 5 p.m. MDT, Hildale assistant fire chief Kevin Barlow said.
The flood "obviously caught these people off guard," Barlow told The Associated Press. "Witnesses say they were backing out of it trying to get away from it and it still swept them in."
One survivor was found downstream at a bank in town. Barlow didn't have information on the others who were rescued.
Officials said the bodies of two people were recovered in Arizona about two and a half miles downstream.
In a separate incident in another part of Utah, officials at Zion National Park say four people were killed and three were missing after flash flooding swept through the park.
In a press release, the park said that rangers received word of a group of seven individuals canyoneering in Keyhole Canyon shortly before the flooding began. Four were confirmed dead. Names were not being released, pending notification of kin.
Back in Hildale, CBS News' Ben Tracy reports that the city of nearly 3,000 is prone to flooding, but not like this.
Barlow said the rescue effort was ongoing through the night but scaled back because of treacherous conditions in the sister towns of Hildale, Utah, and Colorado City, Arizona.
Utah Gov. Gary Herbert says he's heartbroken to hear about the flash flooding and said in a statement Tuesday morning that Utah was offering all state resources to help the towns with the search and rescue effort.
D.J. Bolerjack of CBS affiliate KUTV reports that the search area was lit by flood lights as heavy machinery combed through a mix of debris and mud overnight. Volunteers, including women in long dresses, worked alongside men looking for people who were swept away.
Barlow confirmed seven deaths Monday night, while the Utah Division of Emergency Management said in a later Facebook post that an "additional victim has been located below the Central Street crossing bringing the total number of confirmed fatalities to 8. There are still 5 unaccounted for."
During a press conference Tuesday afternoon officials said they had recovered a ninth body. The death toll rose to 12 by Tuesday evening.
The floods came after heavy rains fell in the canyons just north of the towns, sending waves of water barreling through the streets. The towns sit at the foot of picturesque red rock cliffs about 315 miles south of Salt Lake City.
CBS affiliate KPHO reports one resident sent them a video of debris-choked water pushing under a bridge. The longtime resident of Colorado City, Guy Timpson, said he saw the vehicles wash away in what he described as "by far the biggest flood I've ever seen in my life."
"Those two vehicles washed down in just a moment," he continued. "It was just heart-wrenching."
The women and children were in an SUV and a van on a gravel road north of the towns, Barlow said. It appears they were coming back from a park in the area when the flash flood hit, he said.
The National Weather Service had issued a flash flood warning earlier in the day, leading nearby Zion National Park to close all slot canyons as a precaution. Barlow said he doesn't know if residents were aware of the warning.
He said the water was well above normal flood stage. "This was several feet deep, at least, and even more treacherous in the narrow channels."
Members of the sect, whose members believe polygamy brings exaltation in heaven, are believed to be discouraged from watching TV, using the Internet or having much contact with the outside world.
More than four years after Jeffs was sentenced to life in prison for sexually assaulting underage girls he considered brides, the community is split between loyalists who still believe Jeffs is a victim of religious persecution and defectors who are embracing government efforts to pull the town into modern society.
The community is a patchwork of upscale, elegant residences surrounded by large walls and unfinished, dilapidated houses that remain just as they were in the early 2000s, when Jeffs ordered that all construction stop in Utah to focus on building his compound in Texas.
The flooding also caused other, less serious problems. Barlow said several blocks of homes are without power and water due to the flooding.
"We're pretty used to flash flooding, but this is significantly more than what we're used to," Barlow said.
The National Weather Service is forecasting scattered rain and thunderstorms Tuesday in the area.