WASHINGTON — WASHINGTON -- Freddy Richter laughs, splashes and smiles as he paddles through a swimming pool at the Jewish Community Center in Rockville over the summer. It's clear at eight-years-old, Freddy has the heart to be a great swimmer.

Skills are the next challenge.

"He's on the autism spectrum," said Freddy's dad, Eckhart Richter. "It wasn't until both Freddy and his brother Andy were in this program that allowed me to really see how we should approach teaching them to swim."

Freddy is a student of Sports Plus swimming classes in Rockville. They are designed specifically for children with autism. For the past eleven years, co-founder Tom Liniak has built a curriculum to help children with autism learn to swim, and understand the dangers of wading into water without the right skill set. He and his wife, Natalie, started the program when their son John was a child. John is living -and thriving -with autism.

"They’re really, really going to be attracted to water," Liniak said. He said he's seen children jump into water, sink, sputter when they rise to the surface, then jump in again without hesitation.

"They might be attracted to water and might not even think about the fact that they don’t have skills," he said.

Autism Spectrum Disorder is a growing problem in the United States, according to the Centers for Disease Control.

The agency reports one in 68 children were placed on the autism spectrum in 2016. That rate will jump to one in 59 children this year.

Doctors say within the data is a big, yet understudied problem. Children with autism tend to wander off or run away, and not enough parents are prepared for the behavior or know how to stop it.

“I relived this location in my mind over and over again ‘what if?’”

Mary Wimpy had not set foot in this Germantown park in almost a year when she finally visited with WUSA9. Horrible memories kept her away.

“This place for me is my nightmare,” Mary said. “The wind was whipping. It was really, really cold that day.”

In early March 2017, her daughter, Sahara, was home with a babysitter while Mary was at work. A close watch was critical. Sahara was seven-years-old then and living with autism.

“At that time she could not talk at all,” Mary said. “She didn't say words or even sentences.”

Around noon, Mary’s phone rang. Her heart started racing.

“At about 12:20, I got a call from Montgomery County police that she was missing,” Mary said. “I immediately went into a panic.”

Sahara wandered off alone. A frantic search began.

“All I could think about was her being out there. I knew she didn’t have a coat because her coat was still hung up on the hook.”

After more than an hour, a friend on the search called Mary to let her know a Montgomery County police officer found Sahara. She was face down in water, hypothermic, and close to death.

“To see her I wouldn’t wish on my worst enemy in the state she was in,” Mary said. “I cried, I begged for her to open her eyes. I kept saying ‘It’s me, Mommy. Open your eyes’.”

MORE: Resources on How to Stop Wandering

Fortunately, police rescued her in time. Now, nine-years-old Sarah is vibrant and cheerful. She’s recovered completely.

“We lived in that house for five years,” Mary said. “She has never opened that front door or walked out of it. Ever.”

Mary said no one warned her children with autism have a tendency to wander. She isn’t alone.

A 2012 study published in the medical journal Pediatrics showed up to half of children surveyed wandered away at least once after age four. The report revealed another startling trend: half of the parents surveyed said no one warned them about wandering or told them how to stop it.

Katherine Williamson is an occupational therapist at Children’s National Hospital in Northwest D.C. She works with children with autism like David Landrum.

“He doesn't necessarily just like walk off, he bolts,” she said. “It’s hard to tell what would set him off, or what would be to over-stimulating. He might be in tune to something none of us are even paying attention to.”

At eight-years-old, David is learning to control his emotions, identifying what overwhelms him and what prompts him to run away.

WUSA9 spent the morning with David as he and Katherine performed physical exercises to help David find a sense of calm.

“I’m sensitive to loud noises,” he said. “I cover my ears and if I hear a loud toilet flushing, it’s -oh my god,” David said shaking his head.

“When we first noticed some real problems was when we were -when he was small -and I would take him to the restroom and the hand-dryers in there, oh he could not stand it,” said Ron Landrum, David’s dad.

“He would leave,” Ron said. “He would go out the door.”

“They can disappear in a moment, that’s for sure and whenever that happens you can feel your heart come up into your stomach, into your throat,” Ron added.

Montgomery County Police Officer Laurie Reyes built her career on finding children with autism who’ve wandered away.

MORE: Tips From Montgomery County Police for Parents and Caretakers of Children with Autism

“Who in here has been on a call involving someone who has autism?” she said at a recent training. “Just about all of us.”

Reyes runs an autism-response class for police officers. She says some of the reasons kids might run include loud noises, bright lights, or they want to explore but can’t communicate their desire.

Reyes said children with autism often have no fear of consequences, may not respond when spoken to, may run away and might have sensitivity to light and to touch.

She said her agency searches for children with autism two to five times per week, but not enough parents call 911 when the child wanders away.

“This summer we had five close calls with individuals with autism in bodies of water,” Reyes said. “My biggest fear and the fears of officers is having a tragedy.”

With Sahara’s experience behind her, Mary has a message for parents of children with autism.

“Reach out to your neighbors,” she said. “Let them know you have an autistic child. If they see the child outside and there’s nobody with them, you have to call the police.”

Mary added child proof devices to the doorknobs in her house to make sure this never happens again.

*Editor's note: This story has been updated to better reflect how Sports Plus was created.