At least 16 people, including nine children, were killed this week when flash flooding struck Zion National Park and a Utah border town best known as the headquarters of a fundamentalist Mormon sect.

12 of the victims were reportedly returning from a day trip to their homes in Hildale, Utah on Monday when a wall of water and debris suddenly appeared behind them, sweeping their vehicles away. From CNN:

“It came onto the street behind them and washed them into the ravine, and the dropoff there is 20, 30 feet. So the witnesses say the vehicles were just gone,” [Hildale Mayor Philip Barlow] said.

The rush of water was so intense it washed the two vehicles hundreds of yards downstream, and one vehicle was found a quarter mile away, in the creek, the mayor added.

Officials say three children survived the incident and one person is still missing.

On Tuesday, the bodies of four hikers were found in nearby Zion National Park after it too was hit by flash floods, the Associated Press reports. A park spokesperson said three more hikers remain missing.

[Image via AP Images]