Flash flooding in Utah has claimed the lives of 19 people, including 12 who died after two vehicles packed with families that had gone to watch torrential waters ran into a “wall of water” filled with debris on Monday.

Seven Zion National Park visitors died after they went missing in Keyhole Canyon, the park service announced Thursday. The identities of the canyoneers won’t be released until their families have been notified, the agency said.

In Hildale, Utah, a torrent carried two cars, filled with 13 children and three women, downstream from the town best known as home to a secluded polygamous community, the Associated Press reported. Two of the bodies were found in Arizona. Hildale sits on the Utah-Arizona border.

A 6-year-old boy still remains missing, AP reported. Three children were rescued Monday night, and the victims are as young as 4, the news agency reported.

At at news conference Tuesday, Hildale Mayor Phillip Barlow described the incident as a “100-year flood” and a “wake-up call for the community,” the Salt Lake Tribune reported.

The flooding in the Maxwell Canyon area also hit Hildale’s sister town, Colorado City, Ariz.

The search on the banks of Short Creek continued Tuesday, as officials warned the public to stay away. “The creek is still running high and the area is unstable with large volumes of mud and debris,” Washington County Emergency Services said in a statement.

“This is going to be a heartbreaking night,” the Utah Division of Emergency Management said in a statement Monday night. “Our prayers are with the search and rescue teams and those families who are aching for their loved ones.”

Hildale Assistant Fire Chief Kevin Barlow told the Tribune that the families in the two cars were “well back from the flood” that had been raging after a heavy downpour that began in the mid-afternoon local time and continued into the early evening.

They were “caught unawares” by the water that suddenly surged around them, ultimately causing the ground beneath them to give way, he said. “Witnesses say they were backing out of it, trying to get away from it and it still swept them in,” the assistant fire chief told the AP.

Numerous rescues were underway during and after the rain in the area, which is notorious for flash flooding.

Hildale residents told the AP that it’s common for residents to come out and watch the heavy downpours.

“People go out on the streets and kids will start playing,” Chris Wyler, 38, told the news agency. “But this storm that hit yesterday, it was just so severe and so sudden.”

This story, originally published Sept. 15, has been updated.