Shortly after the sniper shootings began, Michelle Yu's 10-year-old daughter, Catherine, crept into her older sister's room and took her big stuffed dog Schubert, a family favorite. Now Catherine sleeps with the dog nestled safely between her head and the top of the bed.

"I said, 'Silly girl, why do you let Schubert take up all the space?' " said Yu, who lives in Potomac. "She said, 'Mommy, Schubert can protect me so that the bullet can't get into my head.' " 

The shootings that have left 10 people dead and three seriously wounded in the last three weeks have terrorized much of the Washington area, but most of all, its youngest and most vulnerable residents.

The apparent randomness of the attacks, their wide geographic distribution, the fact that one victim was a 13-year-old boy and, most recently, the revelation that the sniper has made a vague but direct threat against children have deeply traumatized some youngsters, according to parents, therapists and pediatricians interviewed across the region yesterday.

"Your children are not safe anywhere at any time," read the disturbing postscript on the note left at the scene of Saturday night's shooting in Ashland, Va., and revealed Tuesday evening by Montgomery County Police Chief Charles A. Moose.

Yesterday morning, Darby Gingery's son, Gunnar, 12, appeared at the breakfast table with a copy of the newspaper carrying stories on the threat.

"His eyes were wide as saucers, and he said, 'Look! Even kids aren't safe!' " recalled Gingery, who lives in Potomac.

Her 10-year-old daughter, Grayson, said the sniper is about the only thing she and her friends talk about, dashing for cover every time they see a white van roll by.

"The teachers don't talk about it," said Grayson, who attends St. Francis Episcopal Day School. "They don't want to scare anyone. They say we're safe. They say that every day. But I have this feeling he's going to come closer to our school."

Many parents said they are struggling for the words to explain this latest threat. It was difficult enough already, they said.

"We have a whole new vocabulary to teach our children," said Donna DeSoto of Fairfax, the mother of an 11-year-old daughter and a 16-year-old son. Sniper. Assault weapon. Lockdown. Code Blue. Dragnet. "The parenting books don't prepare us for this."

The range of anxiety is far-reaching: kindergartners who suddenly won't go to the bathroom alone; teenagers who can't sleep through the night; middle-schoolers who have lost their appetite.

Fairfax psychologist Kathleen Skilton tells of a 7-year-old boy who unexpectedly asked his mother, "What do I do, Mom, if you get shot?" and of a little girl who wanted to know, "Will it hurt if thesniper shoots me?" 

Dori Wooten, a Mount Rainier mother of four children ages 2 to 12, said that every time their car is alongside a white truck, "my kids are freaking out. One time, we pulled up next to a big white van and my daughter was whispering and pulling and yanking my shirt, [saying] 'Mommy, Mommy, it's a white truck. Don't pull up so close.' " 

The sniper assault comes on top of a difficult year for children, who have weathered some anxiety-provoking events: the Sept. 11 terrorist attack on the Pentagon, the anthrax-tainted letters that brought much of the area's mail to a standstill and the discovery of malaria-positive mosquitoes in Northern Virginia.

"I think all of us parents are feeling almost a sense of mourning," said Dan Shapiro, a developmental and behavioral pediatrician in Rockville and the father of four boys. "A relatively protected era in the history of childhood seems to be ending. . . . It is a sad time in many ways."

Centreville parent Suzy Hunt believes that it's better for children to hear news about the sniper from their parents than from their peers. Rumors can run wild at school, she said.

But it's not always easy to know what to say and when.

Yesterday morning before school, Hunt decided to tell her younger daughter, Lauren, 11, about the sniper's threat against children. Lauren reacted angrily, she said, and began talking about starting a reward fund to catch the gunman or help his victims.

In contrast, Hunt said, she took one look at her 12-year-old daughter, Sammy, and opted to delay giving her the upsetting news until after school. Sammy seemed to have a lot on her mind during breakfast, Hunt said, and she could see fear in the child's eyes.

Some parents with younger children are trying to shield them altogether from the news.

Chris Cerva of Herndon has turned off all televisions and radios in her house. Her children, ages 4 and 6, are just too young to handle what they might hear, she said.

When they ask why their school trips are being canceled or why they can't go outside, she makes up an excuse. She hasn't mentioned a word about the sniper.

And sometimes parents just don't know what to say. Silver Spring 13-year-old Christian Aragon said that he watches the news on television with his parents but that they have few answers to his questions about the sniper.

"I question myself," he said. "What's the reason for all this? What is he trying to prove?" 

Even children who appear unaware of the situation or who seem to be accepting it calmly may surprise parents with their reactions.

Ellen Beekman's daughter Emily, 6, loves the indoor recess that her Fairfax school -- like most in the region -- has instituted while thesniper manhunt continues.

But last week, Beekman said, as she prepared for her nightly walk, Emily's hidden fears surfaced. "She was waving and crying," Beekman recalled. "She said, 'Please don't go. I don't want the bad person to shoot you.' " 

Lisa Meier, a psychologist with the Women's Center in Vienna, said parents will tell her that their 5- and 6-year-olds are showing signs of anxiety -- wetting the bed and being clingy -- but assure her that the children know nothing about the recent events.

"And I say, 'Well, let me bring them in and let's see what comes up,' and it comes up," but the parents had no idea that was on their children's minds.

Even the briefest exposure to news of the sniper can have profound ramifications.

Susan Lynch of Bethesda said her 6-year-old, Andrew, apparently caught a glimpse of the news while tuning in to a children's program. Suddenly, she said, he was fixating on the case, certain that he had seen the white van police were looking for and worried because he had failed to get the tag number.

"I couldn't imagine where he'd gotten that level of detail and this feeling of responsibility about missing the license plate," Lynch said. "I had to get him off this track and let him know it wasn't his responsibility to catch the bad guys."

Many children are able to develop coping strategies. Fairfax mother Danielle Bussell's 7-year-old son, David, has asked his parents to read him lots of stories with happy endings.

"He says he needs to have hope -- that he wants to hear a lot of stories right now where the good guys win," Bussell said. "It's very sad. Your kid is saying, basically, 'Bolster me. Give me hope that we're really going to win this battle.' " 

Skilton said the timeless themes of children's literature can teach youngsters valuable lessons about the current situation: that bad things can happen to children, that adults are not all-powerful and that stopping evildoers doesn't often happen quickly or easily.

"Anybody who's read 'Harry Potter' knows that the bad guys are really, really bad and they're really, really hard to catch," she said. "And you don't always know who the bad guys are."

Parents with strong religious beliefs say they and their children take comfort in their faith at such a time.

Kathy Reid of Centreville encourages her daughters, ages 17 and 22, to turn to God.

"I want to give them strength," she said. "I'm not ready for my children to die, I'm not ready to die, but I've been telling them that when God wants you, it's your time, you have no control over it."

Judith Bernardi, a psychotherapist specializing in death and grieving, said parents need to play down their own fears and maintain children's routines. Keeping home life predictable gives children a sense of security, she said.

"For many people, the fear of not being in control, not knowing what will happen, has a life of its own," said Bernardi. "That needs to be contained and controlled around children so that they don't become very, very fearful."

But checking one's emotions is not easy when one's children are affected. "It's very frustrating," said Fairfax mother Deb Schenaker, whose children are 4, 11 and 13. "I find myself very angry with thesniper, whoever that turns out to be. . . . He's pulled the plug on innocence."