(CNN) -- Seven-year-old Jonathan Reyes sank his hands deep into his jeans pocket as anxiety wrinkled his face. He swallowed hard, twisted and turned nervously.
"It could be very hot," warned his dad, Augustine Reyes.
Jonathan whimpered softly as he and his parents approached what was left of their house, one of more than than 500 structures razed by wildfires raging in Los Angeles County. Their Sylmar home of the last 10 years was no more.
The Reyeses were anguished about explaining the loss to their son. Any 7-year-old would find such loss devastating, but Jonathan is even more fragile. He has autism.
"You ready?" his father asked extending his hand. Jonathan nodded and put his tiny hand in his father's palm. They headed to the house.
Children with autism are focused on a daily routine with fixed habits and familiar surroundings. Although their traits and abilities vary depending on the individual, changes to their daily routine can be very disruptive, shattering their feeling of security and triggering unexpected behavior, experts say.
"Many of them expect to see the same things every day, to have things the same every day, to expect when they come home from school to see the same house they usually see," said Dr. Tanya Paparella, a professor of child psychiatry at UCLA.
"For a child [with autism] to see something completely different, to see a house no longer there, it can be extremely traumatic."
The child may not understand the situation and have breakdowns. When Hurricane Katrina struck, many displaced families were left wondering how to explain the changes to their children with autism, said Lynda Geller, a professor of child and adolescent psychiatry at the New York University's School of Medicine.
"For the child, it's a loss of understanding of the world," she said. "Kids like that have extreme aversion to any changes. It knocks their socks off to have everything different."
The child may throw more tantrums or flap his or her arms more frequently, to show stress and anxiety, experts say.
When the Reyeses' home burned down, their first concern was how Jonathan would react.
On Tuesday, they brought Jonathan to the site of their home to see if any of his cherished Hot Wheels cars survived the fire. And maybe, they hoped, seeing the house would help their son understand.
"One of the first things he asks is, 'Are we coming home today?' " said Jan Reyes, Jonathan's mother. "Now that he sees this, maybe it will bring closure for him."
As they drove to their house, instead of trees and a neighborhood, they saw a valley of metal and ash.
Pulling on heavy-duty gloves and strapping on masks, Jonathan and his parents shuffled through the debris searching for one of the boy's treasures -- his Power Wheels, a beloved blanket he always sleeps with or maybe his tricycle.
A favorite toy is like "a familiar anchor in the world" "for a child with autism, Geller said. It can comfort the child when their world is in flux.
"We're going to try and find your cars, OK?" said his mother. Jonathan nodded.
Shards of glass and pieces of their home crackled underneath their footsteps. Pieces of an air conditioner, the skeleton of a jukebox, molten bed frames, Christmas ornaments jutted from the ground.
"There's nothing here. There's nothing here," Augustine Reyes said, holding a gutted time capsule that once held Jonathan's baby tooth, their family photos and baby photos.
"I guess everything's gone."
"Every time I turn around I find another memory -- Christmas plates," said his wife, Jan Reyes, stopping to wipe back tears.
Since being forced to leave their home a few days ago, the Reyeses have noticed Jonathan behaving more anxiously than usual.
"He's been very nervous, very clingy," his mother said. "I don't know why. He thinks Mom and Dad are going to leave him."
When Jonathan returned to his house Tuesday, he was pensive, focused on his quest to find his Hot Wheels. His shoulders drooped and he shuffled around the debris.
"He's doing a lot better than his mom or dad, believe it or not," Jonathan's mother said. "Time will tell. He's never seen anything like this.
"I think we're going to have to talk to him for a long time to get him to accept the reality. I don't think it's hit him yet."
The family found Jonathan's tricycle in the rubble. The tires had melted, the frame rusty and burned, but intact. Jonathan asked if they could get new tires. And Jonathan made another discovery: a small metal square. Hoisting the square, Jonathan said, "That was from one of my cars."
Mattel, the company that makes Hot Wheels has offered to donate new toys for Jonathan. His mother called the offer, "equivalent to us winning the lottery."
After an afternoon of searching, the family loaded the tricycle in the back of the pickup truck. They walked hand in hand from the front steps to where their door would have been and looked at the debris where their house once stood.
"We've been blessed. We'll get over this. ... Won't we?" said Augustine Reyes, pulling Jonathan close.
"Um, yeah," said Jonathan and leaned into his father's shoulders.
"Now that he sees this, I hope this brings closure to him and my wife," said Augustine Reyes.
"There was a lot of happy memories in this house. We just had to come here to say goodbye."