They might not want to talk about the gunshots or the screams. But their toys might start getting into imaginary shootouts.
Last week's school shooting in Connecticut raises the question: What will be the psychological fallout for the children who survived?
For people of any age, regaining a sense of security after surviving violence can take a long time. They're at risk for lingering anxiety, depression, post-traumatic stress disorder.
But after the grief and fear fades, psychiatrists say most of Newtown's young survivors probably will cope without long-term emotional problems.
"Kids do tend to be highly resilient," said Dr. Matthew Biel, chief of child and adolescent psychiatry at MedStar Georgetown University Hospital.
And one way that younger children try to make sense of trauma is through play. Youngsters may pull out action figures or stuffed animals and re-enact what they witnessed, perhaps multiple times.
"That's the way they gain mastery over a situation that's overwhelming," Biel explained, saying it becomes a concern only if the child is clearly distressed while playing.
Nor is it unusual for children to chase each other playing cops-and-robbers, but now parents might see some also pretending they're dead, added Dr. Melissa Brymer of the UCLA-Duke National Center for Child Traumatic Stress.
Among the challenges will be spotting which children are struggling enough that they may need professional help.
Newtown's tragedy is particularly heart-wrenching because of what such young children grappled with - like the six first-graders who apparently had to run past their teacher's body to escape to safety.
There's little scientific research specifically on PTSD, post-traumatic stress disorder, in children exposed to a burst of violence, and even less to tell if a younger child will have a harder time healing than an older one.
Overall, scientists say studies of natural disasters and wars suggest most children eventually recover from traumatic experiences while a smaller proportion develop long-term disorders such as PTSD. Brymer says in her studies of school shootings, that fraction can range from 10 percent to a quarter of survivors, depending on what they actually experienced. A broader 2007 study found 13 percent of U.S. children exposed to different types of trauma reported some symptoms of PTSD, although less than 1 percent had enough for an official diagnosis.
Violence isn't all that rare in childhood. In many parts of the world - and in inner-city neighborhoods in the U.S., too - children witness it repeatedly. They don't become inured to it, Biel said, and more exposure means a greater chance of lasting psychological harm.
In Newtown, most at risk for longer-term problems are those who saw someone killed, said Dr. Carol North of the University of Texas Southwestern Medical Center, who has researched survivors of mass shootings.
Friday's shootings were mostly in two classrooms of Sandy Hook Elementary School, which has about 450 students through fourth-grade.
But those who weren't as close to the danger may be at extra risk, too, if this wasn't their first trauma or they already had problems such as anxiety disorders that increase their vulnerability, she said.
Right after a traumatic event, it's normal to have nightmares or trouble sleeping, to stick close to loved ones, and to be nervous or moody, Biel said.
To help, parents will have to follow their child's lead. Grilling a child about a traumatic experience isn't good, he stressed. Some children will ask a lot of questions, seeking reassurance, he said. Others will be quiet, thinking about the experience and maybe drawing or writing about it, or acting it out at playtime. Younger children may regress, becoming clingy or having tantrums.
Before second grade, their brains also are at a developmental stage some refer to as magical thinking, when it's difficult to distinguish reality and fantasy. Parents may have to help them understand that a friend who died isn't in pain or lonely but also isn't coming back, Brymer said.
When problem behaviors or signs of distress continue for several weeks, Brymer says it's time for an evaluation by a counselor or pediatrician.
Besides a supportive family, what helps? North advises getting children back into routines, together with their friends, and easing them back into a school setting. Studies of survivors of the Sept. 11 terrorist attacks found "the power of the support of the people who went through it with you is huge," she said.
Children as young as first-graders can benefit from cognitive-behavioral therapy, Georgetown's Biel said. They can calm themselves with breathing techniques. They also can learn to identify and label their feelings - anger, frustration, worry - and how to balance, say, a worried thought with a brave one.
Finally, avoid watching TV coverage of the shooting, as children may think it's happening all over again, Biel added. He found that children who watched the 9/11 clips of planes hitting the World Trade Center thought they were seeing dozens of separate attacks.