Parents should also realize that increased anxiety after an event like this is normal, experts say, even if the attack happened in another country, because social media makes the world feel very small.
"Over time, however, in allowing questions and shared thoughts along with reassurances about efforts by your family and security to increase safety while living your lives, anxiety should diminish," said Saltz.
Parents should keep an eye out for "dramatic changes" in behavior such as the way their kids interact with family and friends, or if they experience a sudden drop in grades, said Kelly Ward Becker, chief executive officer of Family Lives on Foundation,
which supports the emotional well-being of grieving children.
"It's important to keep the channels of communication open to keep a pulse on your child's reactions and feelings," she said. "Acknowledge their emotions and legitimize whatever feelings they are experiencing, which may range from sadness, anger or apparent indifference."
When young people are the targets and the victims, it "touches parents' deepest unthinkable fears of loss," said Dr. Claudia Gold,
a pediatrician, infant mental health specialist and author of "The Development Science of Early Childhood: Clinical Applications of Infant Mental Health Concepts From Infancy Through Adolescence."
"While a wish to reassure might be our first instinct, what is needed is primarily to listen," said Gold. "More than finding the 'right' thing to say is to use our own comforting presence."
After an attack, it's more important than ever for parents "to remain in check in relation to their anxiety," said Ferrara, who has been in private practice for more than a decade.
"If adults show an excessive level of anxiety and vulnerability, that will certainly create higher anxiety in children," she said.
Ferrara, Gold, Saltz and other parenting experts offer a range of tips on how to reduce anxiety in children -- and stress that the age of children and their temperament really determines what -- and how much -- to share.
Limiting media exposure is key
If possible, children younger than 5 do not need to be told about what happened or exposed to any of the media coverage, said Ferrara. "Keeping to routine is the best way to reassure children about the safety of their immediate world," she said.
Children ages 6 to 11 need just basic facts and minimal exposure to media coverage, she said, adding that there are definite lessons from what children saw in the media following the September 11, 2001, attacks. She points to studies
that children who had repeated and prolonged exposure to media images had more difficulty with anxiety than kids with less exposure.
In a statement after the 2015 Paris attacks, the American Academy of Pediatrics
urged parents to be careful with images that children see. "As pediatricians, we know that violence can have lasting effects on children even if they are only learning about it through the media," the statement said. The organization offered more resources for parents
on how to talk to children about mass tragedies.
"A child will store the event in memory based on the narrative you assign the event," Ferrara said. "For this age range, stick to basic facts and turn off the TV."
Saltz agrees, and said parents of young children should "stick to basic broad-stroke facts" and avoid any "nitty gritty details that are disturbing."
Parents should then communicate to their children an openness and willingness to talk, answering their questions and listening to their feelings, she said.
"Make it clear you understand their feelings. In other words, don't blow them off or avoid their feelings. This can be hard when they're (being) upset makes you more upset," said Saltz, author of "The Anatomy of a Secret Life."
"But expressing their feelings will help them to cope. Then be reassuring about all of the security at work protecting us, and how rare an event this really is."
How to reassure your child
Reassurance is one of the most important things parents can provide children during a time of tragedy, when they fear it could happen to them, said Dr. Glenn Saxe,
chairman of the department of child and adolescent psychiatry at NYU's Langone Medical Center
, in a previous interview.
"The first kind of thought and feeling is, 'Am I safe? Are people close to me safe? Will something happen? Will people I depend on protect me?' " said Saxe, who is also director of the NYU Child Study Center.
"You want to be assuring to your child, you want to communicate that you're ... doing everything you can do to keep them safe," Saxe said. "You also want to not give false assurances, too. And this is also depending on the age of the child. You have to be real about it as well."
It helps, too, for parents to acknowledge their own fears about how to keep children safe, even amid unpredictable violence, said Gold, who is also author of "The Silenced Child: From Labels, Medications, and Quick-Fix Solutions to Listening, Growth and Lifelong Resilience."
It might seem counterintuitive, but acknowledging uncertainty can help parents connect with their children, and lead to a stronger sense of safety and security.
She points to how people have taken to the streets after recent attacks expressing that they will not be afraid. "When our children can sense that courage in us, they too will not be afraid. When we can manage our own anxieties, we are in a better position to listen to the responses of our children, which may differ according to their unique individual qualities."
Dr. Joe Taravella,
supervisor of pediatric psychology at NYU Langone Medical Center's Rusk Rehabilitation, said parents should not be afraid to show their own emotions about tragic events. Children pick up on the "emotional temperature that's in the home," even if we think we're hiding how we truly feel, he said.
"We are our children's role models, so we should be leading by example at all times and when we're sad," said Taravella. "We talk about our sadness so we can talk about us being fearful and sad that this happened, but then, I always try and end on the positive to help them cope or deal with it, that we are a family and that we support each other as a family."
Parents should also be mindful of any changes in their children's behavior after learning about a tragedy, Taravella said.
"I would try and put their behaviors into words like saying, 'I see that you've been more cranky lately or more upset, I'm wondering if something's going on, if you feel upset about something,' " he said, which might help them communicate what they are feeling.
Helping teens open up
For teens, who will most likely have heard about violent events or attacks through social media or news coverage, it is best to start by asking what they know, Ferrara said. Parents should also not assume their children are processing the events or trauma surrounding the events the same way they are, she added.
"Initially, it is possible they may not have much to say," she said, but they might revisit the topic when something connects to them personally.
"Events like this sometimes defy language, and a teen may struggle to discuss. However, remain open for these emerging adults. They need to know that they matter and that the world's complexity is in dire need of their taking the time to think about and understand what it means to be global citizens," she said.
"It is a shared responsibility that none of us, parent or young adult child, is able to avoid."