Family of Sloan Mattingly, 7-year-old girl who died after getting buried in sand, speaks out

Therese Mattingly's two children were playing in the sand while the family was vacationing in Florida last month when suddenly "it just became chaos and horror," the mother told "Good Morning America."

Sloan Mattingly, 7, and her brother, Maddox Mattingly, 9, were both buried when the hole they were digging at the Lauderdale-by-the-Sea beach collapsed on Feb. 20, authorities said. Maddox was uninjured but Sloan died at the hospital, her family and police said.

Now, her parents are speaking out for the first time to honor their daughter and raise awareness about beach safety ahead of spring break.

"We're the people that other parents or family members kind of roll their eyes at because we're a little overprotective most of the time and think of everything," Therese Mattingly told ABC News correspondent Erielle Reshef in an exclusive interview from the family's home in Fort Wayne, Indiana. "When we go to the beach, we think of water safety. And this never, ever once crossed my mind."

Watch the Mattinglys' full interview on "Good Morning America" Thursday at 7 a.m. ET.

Her husband, Jason Mattingly, told "Good Morning America" that the day had been "perfect" up until then.

"We were just relaxing," he said. "We were just getting ready to end our day there. And then that's when the incident happened."

Therese Mattingly said the collapse happened "really fast."

"That part just hurts really bad because it didn't matter that we were literally right there," she said. "It was just a hole, and then there's nothing."

Many beachgoers came over to help as they frantically dug the children out, from helping dig to calling 911, the parents said. Therese Mattingly said once they pulled out Maddox, who was buried up to his chest, a nurse stayed with him while she continued to dig for Sloan.

"Everyone tried their hardest. And unfortunately, it didn't work out in our favor," Jason Mattingly said.

The father said the sand collapse happened in an instant.

"It's kind of a blur, and it's probably maybe in my mind protecting itself, but it just happened so fast," he said. "And in my mind I had her in my hands, but the weight of the sand was too much."

"It didn't matter that we were literally right there," Therese Mattingly added. "It was just a hole. And there's nothing."

Sloan, who was a first grader at Lafayette Meadows School, was "a beam of light," and pure "joy," her mother said.

"She would come out in the morning and she would fist pump you right out of bed," Therese Mattling said.

She was a fan of Taylor Swift and loved to make friendship bracelets for her family, friends and teachers, her mother said while wearing some that her daughter had made.

Maddox and his sister were each others' "built-in best friends," though he became an only child "just all of a sudden," Therese Mattingly said.

"I think he's holding a lot in," she said when asked how he is doing. "There's a lot of things we have in motion to help him with that and to help us help him."

"I think he'll always be a little different now, but we're willing to do whatever we need to do to make sure he has the help to kind of process this and move forward with Sloan in his heart," Jason Mattingly added.

Jason Mattingly said the support they've received from friends, family and strangers who have reached out from across the globe have helped in the weeks since Sloan's death.

"The love and support that we received is overwhelming," he said. "We've read every letter. We really appreciate all the support."

The family hopes that by speaking out about what happened to Sloan, they can help prevent another family from going through the same tragedy.

"I don't know what steps to take in order for that to happen -- for, you know, signage or lifeguards or patrol," Therese Mattingly said. "But hopefully we can make some sort of change from this."

Chris Vincent, mayor of Lauderdale by the Sea, thanked the family for working with them to inform others about what can happen with sand holes.

“First and foremost, our heavy hearts remain with Sloan’s family,” Vincent said in his statement. “As a father myself, I can’t fathom what they are going through. I want to thank them for staying in contact with us as we develop a national public safety campaign in Sloan’s memory. We will share it with as many coastal communities as possible to help prevent another unimaginable tragedy. We’re also discussing how we monitor our beach, a local Ordinance to ban digging on our beach, and the best way to honor Sloan.”

According to Karen Daniels, a physicist at North Carolina State University who studies how sand moves, for safety she advises beachgoers not to go deeper than the knee of the smallest person when digging a sand hole. If the hole is too deep, the walls can collapse, covering a person in the sand, she said. The sand can be heavy and impede a person from lifting themselves out of a hole to breathe, she added.

Daniels recommends that if you're burying a friend in the sand, it's better not to dig but to cover the friend with sand at the ground level so the foundation is sturdier. Additionally, she advises people to watch out for deep sand holes when walking on the beach as a fall in a deeper hole could lead to a broken limb.