(CNN) - A family gathered at a popular swimming area north of Phoenix to cool off from the desert heat and celebrate a birthday.
Heavy rain was falling eight miles upstream from where they played, but skies were apparently clear where they were. Even if they had heard or seen the flash-flood warning from the National Weather Service an hour and a half earlier on their smartphones, it's hard to imagine they could have anticipated the devastation about to hit them Saturday afternoon.
Summer fires had cleared ridges and slopes of vegetation, so there was nothing to slow the tremendous volume of water that swept down on them so quickly, on land baked to repel water by constant high temperatures.
"They had no warning. They heard a roar and it was on top of them," Water Wheel Fire and Medical District Fire Chief Ron Sattelmaier told the Arizona Republic.
Reportedly up to 6 feet high and 40 feet wide, the waters swept away 14 members of the family, carrying them fast and far downstream.
Nine were killed, including five children ages 2 to 13, police said.
The Gila County Sheriff's Office on Monday identified the nine victims as:
Jonathan Leon, 13; Mia Garnica, 5; Emily Garnica, 3; Danial Garnica, 7; Javier Raya-Garcia, 19; Selia Garcia Castaneda, 57; Erica Raya-Garcia, 2; Maribel Raya-Garcia, 24; and Maria Raya-Garcia, 27.
Hector Miguel Garnica, 27, remains missing. Search and rescue crews worked to find him Tuesday.
The disaster happened near the Cold Springs swimming hole, just north of Payson, in Gila County, and about 90 miles north of Phoenix.
Flooding left behind path of destruction
CNN affiliate KNXV-TV in Phoenix tweeted a photo showing the grim aftermath, which left behind an avalanche of mud and rock that flowed into the swimming hole. The station also posted raw video of a helicopter rescue operation in the area showing muddy water cascading over rocks.
Cold Springs is one of several popular swimming spots in the Tonto National Forest. It is upstream on Ellison Creek from Water Wheel, a larger area. The stretch of river is known for canyons and water channels. A website about Arizona swimming holes said that "the water is so cold it takes your breath away for a few seconds."
But it's difficult to know what's happening upstream.
Rain can fall miles away and sweep down creeks so fast and strong it's hard to outrun or outswim them. The National Weather Service in Phoenix said burn areas, desert washes, low-water crossings and low-lying areas are susceptible to such flooding.
KNXV said dozens of people were swimming in the river at the time of the flooding. Sattelmaier told the station there was no way of knowing how many people were actually there.
Arizona Gov. Doug Ducey said on Twitter that the state would assist in all ways possible.
"Deepest prayers for those lost in the Gila County tragedy, for their families and the entire community," Ducey tweeted.
Trent Shue, a volunteer with the Tonto Recreation Alliance, and other members of his group were marking trails close to Ellison Creek, about three miles from the watering hole, when the storm hit.
"In a short period of time, the creek along the side of the road started to get exceptionally heavy," Shue said. "We could hear the roaring of the flash flood in the distance, and it was something to behold. We made sure to stay far ahead of the rushing water, and finally found a safe spot where we could wait it out."
A video recorded by Shue shows a strong stream of water carrying heavy logs and wiping out trees in its path.
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