The heart-wrenching tragedy that befell Madyson “Maddy” Middleton in Santa Cruz is highly unlikely to happen to any of our children.

But probability is no comfort to parents forever haunted by the murders of 9-year-old Jordon Almgren of Discovery Bay, who police say was stabbed in his own bed by his brother’s best friend in April, and 8-year-old Sandra Cantu of Tracy, drugged and smothered by a friendly female neighbor in 2009.

The savagery of Maddy’s killing, allegedly by a well-liked, 15-year-old neighbor boy inside a mellow Santa Cruz artists colony, has parents and children struggling to make sense of what makes no sense and coping with their anxiety while trying to raise healthy children.

“As an adult, I can’t even process that a 15-year-old would do this to a child,” said Laura Jones, whose daughter attends DeLaveaga Elementary, where 8-year-old Maddy had been a second-grader. “It is terrifying to me.”

Her death has planted nagging questions to play in our heads: How can we keep our children safe in an uncertain world? How can we protect them without keeping them locked indoors or tethered to a leash — and risk creating resentful, rebellious and naive youth?

“We don’t want to start putting kids in little boxes and not let them do things because we’re afraid,” said Mimi Ezray, a therapist at Parents Place of the Peninsula. “We need to say to kids, ‘This is scary, it’s horrible, and it’s very unlikely it will ever come into our lives. But I want to be sure we take safety precautions.’ “

When Jones learned of Maddy’s death, she didn’t tell her 7-year-old daughter about it — that is until all the children at the junior-lifeguard camp began talking about it and her daughter came home asking questions.

“I told her while this doesn’t happen a lot, these kind of things do happen,” Jones said. “I said, ‘It is so tragic, so sad, we can feel heartbroken for Maddy and her family and everyone else whose lives she touched.’ ”

She also spoke to her about safety.

When an awful crime such as Maddy’s happens, it shatters the illusion of the safety of familiarity and spurs families to prepare for an unpredictable danger.

After news of Maddy’s death broke, Santa Cruz-based Kidpower, which focuses on preventing violence and the abuse of children, scrambled to respond to parents’ requests for child-safety training sessions.

“All our classes in the Bay Area filled up in one day,” said Irene van der Zande, executive director of the agency. “People are absolutely horrified and terrified, wondering what they can do and what they should say to their kids.”

Jen Salinas-Holz, a Watsonville parent who has taken Kidpower training courses, said many friends are panicking. “They’re saying, ‘Oh my gosh, now I have to tell my kids to be afraid of people they know.’ ” Instead, Salinas-Holz wants them to understand that being prepared and training children is empowering.

What has thrown so many parents off kilter is that the suspect in the killing, Adrian Jerry “A.J.” Gonzalez, appeared to be such an unlikely perpetrator.

“A lot of parents talk to their kids about stranger danger, but statistics show that most of the abductions and assaults happen with people the victim families know,” said John Winckler of Santa Clara County’s Family and Children’s Services. “Don’t focus so much on the stranger, but teach your kids to be aware of when situations start to change from safe to unsafe.”

DeLaveaga parent Shiri Gradek said she’s long had safety talks with her 7-year-old daughter. “It’s really important you don’t take off, and you don’t go with anyone, whether you know them or not,” she tells her. After Maddy’s killing, Gradek reminded her: “Even if it’s our favorite neighbor, you don’t go anywhere.”

It’s not just teaching rules, but also training kids to think on their feet. Still, it all remains a balancing act.

Ruby Love, of Capitola, has taught her two children to always ask before going to another house or getting into someone’s car. “But I don’t want them to feel afraid or judgmental,” she said. “There’s a fine line between being a hovering helicopter parent but also teaching them to be safe.”

That tension doesn’t ease with adolescence.

Liz Lempkowski, of Fremont, wants her twin 14-year-olds to walk together when going down the street to the store. Having girls go anywhere alone makes her nervous. “You’re not as much of a target if you use a buddy system,” she said.

Salinas-Holz began training her sons, ages 7 and 4, when they were toddlers to cope with situations on their own. What do you do if you get lost in Target? (Answer: Stand still, look around, call your parent’s name, then finally go to a cashier.)

While some questioned on social media how 8-year-old Maddy was allowed to scooter around the complex alone, many parents say they are comfortable letting their kids play close to home.

“I don’t think her parents did anything wrong,” said Dianne Jones, a Fremont mother of three. “They were letting their child be a child.”

What’s so discomforting in Maddy’s case is that the crime took place in a close-knit, easygoing artist community where neighbors looked out for neighbors and their children, and it involved two kids who were often seen on scooters and skateboards and known as anything but troublemakers. Yet now Gonzalez has been charged with murder along with a string of unsettling special circumstances: lying in wait, murder in the course of forcible rape, kidnapping and lewd or lascivious acts with a child.

“I cannot even think too in depth about poor Madyson without feeling a sinking in the pit of my stomach about what can happen so quickly,” said Amy Dahlen, a Santa Cruz parent.

And that is one of the things that makes Maddy’s disappearance and death so disquieting, said Cordelia Anderson, founder of the National Coalition to Prevent Child Sexual Abuse & Exploitation. “There was no warning, nothing you could do.”

So parents must live with the underlying fear that all their best efforts to protect their children may not be enough.

“Communities ought to be safe for kids. They ought to be able to play outside,” van der Zande said. “The reality is sometimes terrible things happen.”

Contact Sharon Noguchi at 408-271-3775. Follow her at Twitter.com/noguchionk12. Contact David E. Early at 408-920-5836. Follow him at Twitter.com/DavidEarlySr.