A flash flood near Payson, Ariz., killed at least nine people on July 15. Authorities say a family of 14 people were swimming in the area and were swept away in the flash flood. (Reuters)

It began as yet another scorching Saturday in central Arizona as scores of families flocked to the cool waters of a popular swimming hole, seeking relief from the 100-degree temperatures in the cities.

Among them was an extended family of 14 from Phoenix. They gathered at the Cold Springs swimming hole in the Tonto National Forest, near Payson, to celebrate Maria Raya’s 26th birthday, their relatives told local media.

At about 3 p.m., it was barely drizzling as the Raya family and others waded in the water and hiked along the narrow canyon, its scenic waterfall and granite rock formations in the backdrop.

Suddenly the adults and children swimming in the canyon heard a roar. As they turned to look upstream, they saw a massive wall of dark muddy water rushing toward them, carrying tree trunks and logs the sizes of vehicles, Ron Sattelmaier, Water Wheel Fire and Medical District fire chief, told The Washington Post, citing interviews with witnesses.

The flash flood’s six-foot tall, 40-foot wide torrents of murky water swept away Raya, her children and several other family members, spanning three generations, while other relatives grasped onto trees waiting to be rescued. By Sunday, nine people had been found dead. Authorities did not identify the dead, but relatives listed the names to local media.

Among these were Raya and her three children, ages 3, 5 and 7. Raya’s husband, Hector Miguel Garnica, 27, was still missing.

Her sister, Maribel Raya, 24, also died, along with Maribel’s 2-year-old daughter Erika and 14-year-old brother Javier.

Celia Garcia, 60, the mother of Maria, Maribel and Javier, was also confirmed dead, along with her grandson, Jonathan Leon, 13.

Other loved ones drove in from out of town as they heard the news of the flood, caused by heavy thunderstorms and rain near the area, the Gila County Sheriff’s Office said. Relatives convened at the canyon to scour the waters for missing relatives into the early hours the next morning. During this search, amid the debris, they found the body of one of the missing children, relatives told the Arizona Republic.

“It’s so difficult to lose an entire family,” Iris Garnica, a cousin of the missing man, told reporters on Sunday, her hand on her face.

All were from Phoenix, the Arizona Republic reported. Four other relatives — a husband, wife and their two children — were rescued by helicopter and treated for hypothermia at a hospital before being released.

Sattelmaier told The Post that while he could not confirm the causes of death, he believed the majority of fatalities were caused by blunt force trauma from the logs, tree trunks and debris carried in the waters.

Hector Miguel Garnica’s sister Carla Garnica, 22, told The Post Sunday that the family was focused on finding her missing brother’s body to bring him home “to be together forever with his family.” She asked for privacy as the family continued to search and mourn.

Earlier Sunday, Carla Garnica told reporters “he has to be found.”

“He’s always said, ‘I’m never leaving my children or my wife,'” Carla Garnica said. “He has to complete his promise.”

Flash flooding is common in both the mountains and the desert of Arizona during the summer monsoon season, Sattelmaier told The Post.

“The rains come so fast and so hard,” he said, “that the soil cannot absorb all the water in these stream beds that are normally dry most of the year.”

The risk of flash floods becomes worse after wildfires and drought, Sattelmaier said. This specific region of central Arizona was hit by wildfires recently, meaning there was less vegetation in the area preventing flooding.

Flash floods, as their name suggests, are unexpected and unpredictable. Meanwhile, he has seen more and more people flocking to watering holes like Cold Springs to escape increasingly hot temperatures. He had seen the Cold Springs swimming area publicized heavily on social media and in nature magazines. The area, part of the Verde River system, is also known as Water Wheel swimming holes or Ellison Creek.

“They don’t expect this wall of water to come rushing at them in a stream bed that’s been dried for the last nine months,” Sattelmaier said. But once a monsoon comes, a dried up canyon “can turn into a raging torrent that can sweep anybody away.”

Over the course of more than four decades, he added, “this is probably one of the worst situations that I’ve been in.”

Mandisa Alexander was also celebrating an early birthday on Saturday, her 21st, when she and her friends made the drive from Phoenix to the Cold Springs watering hole, she told The Post. Though it was a hot and sunny day when they left for the park, it began to hail when they reached the parking lot. They decided to wait it out a bit, a decision for which she is now grateful.

After a short while, the hail stopped and it was barely sprinkling rain outside. So the group of three friends decided to begin the 45-minute hike along the canyon to the watering hole. They were about a mile and a half from the main swimming area when they considered jumping into the water. It was “nice and calm,” she said.

But moments later, “a wall of waves just came rushing down.” The torrential floodwaters raged through the canyon in the area in front of them and behind them.

“If we were five minutes ahead or five minutes behind we would’ve been swept away,” Alexander said.

“I just kind of thought, I’m going to die before I’m going to turn 21,” she added.

They climbed up onto a rock about 15 feet above the water and when they looked down, they saw a man holding on to a young girl, who looked to be about 2 years old, in a tree or bush. The toddler was shivering, but somehow, not crying as the father also remained calm. Both were covered in mud.

His wife was not far from him, also clinging onto a tree, authorities later said.

Alexander and other witnesses called out to the father, trying to offer help. He told them he had been with about 10 other people who had been swept away by the floodwaters.

Alexander and others waded waist deep into the water, trying to carry a large log toward the family to help them to safety. But they worried the waters might pick up again, and were told that rescuers were on their way. As Alexander and her friends hiked out of the park, they saw the body of a woman downstream, washed up on the shoreline.

Matt Owsley, principal at Black Mountain Elementary school in Cave Creek, posted on Facebook that Raya’s son, Hector, was an incoming second grade student at his school and “always one of the kindest little boys I have known. I miss his hugs already!”

Speaking to The Post, Owsley said the school is a “close-knit community” where “everyone knows everyone.” The Raya parents worked in restaurants not far from the school and “were well known by many in Cave Creek.”

“Everyone at school knows Hector,” the principal said. “He makes friends with everyone and finds it hard to pass by without giving a big hug. His smile was infectious. Right now, everyone in our community is trying to make sense of all of this.”

His little sister, age 5, was about to start at Black Mountain the following month.

Other comments on Facebook remembered Hector as a “true ray of sunshine” with a smile that lit up a room.

“My sweet grandson,” said one comment.

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