Editor's note: Kelly Wallace is CNN's digital correspondent and editor-at-large covering family, career and life. She's a mom of two girls and lives in Manhattan. Read her other columns and follow her reports at CNN Parents and on Twitter. This is an update of a story originally published in 2013.
(CNN) -- Not again.
That's what I thought, and what many parents across the country said on social media following a stabbing rampage at a Pittsburgh-area high school on Wednesday.
The difference this time? The suspect allegedly used two knives instead of a gun to attack his 20 victims, leaving several with critical injuries. Thankfully, they're expected to survive, doctors said.
Fort Hood. Aurora. Sandy Hook. Boston. Washington, D.C. Now, Murrysville, Pennsylvania. Another mass tragedy filled with incomprehensible injury, nonstop news coverage and a major question for parents: What do we tell our kids?
Last year, that question was even more difficult for parents in the Washington area since their children -- from elementary school age on up -- were likely to hear about the Washington Navy Yard attacks that unfolded in their backyard and left 12 people dead, as well as the gunman.
After that shooting, Jessica McFadden, a mom of three who lives just outside Washington, said she'd be taking her cues from her children about what to say and when. At the same time, she said she would try to ensure that she and her husband were the first sources of information for their eldest, a 9-year-old son.
"He's going to hear about it, and I don't want him to be scared or to feel as if his world is insecure if he hears about it from kids on the bus," said McFadden, who founded the blog A Parent in Silver Spring.
"So we will be talking about it with him; we will talk about how his school has great safety procedures, how my husband's office has good safety procedures, how our neighborhood is safe, that this isolated incident shouldn't make us more fearful in our day to day," she said.
Sadly, McFadden knows this from experience. A few years ago, McFadden's husband worked inside the Maryland headquarters for Discovery Communications, where a man armed with a gun took three people hostage before police shot him to death.
"We had to talk about it because other adults that came into our family's sphere were talking about it, and so we wanted to make sure that we were the sources for the children's information so that they weren't overly scared hearing about it kind of second hand," she said.
Stephanie Dulli, who lives in Washington with her two boys, ages 2 and 5, initially said she didn't have any plans to tell them what unfolded. "It would accomplish nothing but creating anxiety, especially for my eldest," said the host of the blog Stephanie Says.
But there will come a day when her boys are older, when sadly, another tragedy strikes and when she'll definitely have to talk with them about it. It's not an easy conversation for any parent, but for Dulli, it will be exponentially harder.
Her father was murdered when she was around the same age as her 2-year-old.
"I guess I can only try to do what my mother did. No matter how terrified or scared she was, she never let it affect me," Dulli said. "I will try to do the same. To explain what happened as clearly as I can, reassure and then show by example that we just have to keep going. I may be terrified to let my child go on the overnight trip, but he will never know that."
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.
"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."
Sarah Grosjean, who lives in Leesburg, Virginia, about 45 minutes from the Washington tragedy, hoped to arm her 5-year-old daughter with information when she talked to her.
"I want to be able to make sure my daughter knows, in the event she's ever in something like this ... how would she react? Would she know what to do?" said Grosjean, founder of the blog Capitally Frugal, who said she'll be emphasizing how her daughter should listen to the police or teachers in case of an emergency when her mom isn't around.
Saxe said there are "no hard and fast rules" on the right age to talk to kids about tragedies. He said parents should take into account whether they think their kids will have heard about an event, but -- especially for middle and high schoolers -- parents should bring the subject up.
"I think the most important thing is that the parent communicates a willingness to talk about this, an openness about it, that parents are really attuned to where their children are in this, even just asking a general question, 'Have you heard about this?' and see where your kid goes with that," Saxe said.
Parents should also be mindful of what images their children are seeing on the news and make sure even older ones, who may be watching the nonstop coverage, aren't "flooded with images ... without any attempt to help make meaning for them or bring perspective to it because that could be very difficult," Saxe said.
McFadden said she kept the television off immediately after the Navy Yard shootings, but followed the latest developments via social media on her laptop. She knew she would be only so prepared when she ultimately had the conversation with her kids.
"One of the biggest questions children ask is why," she said, "and that's something that we can't answer."