It's a grim back-to-school accessory for our anxious times: bulletproof backpacks.

Many parents, shaken by the latest atrocities, are worried that their children's school will be the next target.

"It's pretty crazy that you have to worry about that," said Juliet Linden, who lives outside of Sacramento, Calif. But with two school-aged daughters, the possibility of a school shooting is "always in the back of my mind," she said.

"As a parent in this day and age, you worry more and more about things like this."

That's likely why bulletproof backpacks are selling briskly this year.

"The backpack has been a popular item," Yasir Sheikh, whose Skyline USA manufactures Guard Dog Security bulletproof backpacks sold at Office Depot and other retailers, told CNBC. "We have sold out a few times this year."

Office Depot and OfficeMax are among retailers selling the backpacks, which range in price from about $150 to more than $200.

But it isn't only parents who are concerned about shootings. Students are, too.

Nearly 60% of U.S. teenagers between 13 and 17 said they were very or somewhat worried that a shooting could happen on their school's campus, according to a Pew Research Center survey conducted in the two months after the February 2018 mass school shooting at Marjory Stoneman Douglas High in Parkland, Fla.

The same Pew survey concluded that most parents shared their children's concerns.

Brandi Liles and Dawn Blacker are attuned to families' anxiety as child psychologists at UC Davis Medical Center's Children's Hospital. And while they understand the urge parents have to "do something," they stress that it's essential to make sure you talk to your children.

"As parents, teachers and security, we can do much more essential work around this than giving kids a backpack and not talk about it," Liles said.

They encourage adults to consult the National Child Traumatic Stress Network (nctsn.org) to help children after a recent shooting and for teens coping after mass violence.

Look for common reactions, they said. Fears that another shooting is going to happen; a change in activity level or difficulty with sleep. And re-establish routines to reclaim some normalcy.

"Giving your child the space to ask questions — we know avoidance will lead to anxiety," Blacker said.

"You can validate their fears but get them back into their routines as soon as possible," Liles said.

Lori Alhadeff carries a bulletproof backpack. The gear is required equipment for her two sons. And she believes her daughter would be alive if she had had one.

Alhadeff's daughter, Alyssa, was 14 when she and 16 others were killed in the Parkland massacre on Feb. 14, 2018. Alhadeff and husband, Ilan, have since gone on to found Make Our Schools Safe, a national school safety nonprofit group.

"After the tragedy, one of my requirements for my two sons was for them to have a [bulletproof] backpack to go back to school. If all else fails, they'll at least have that," Alhadeff said.

"There are people who won't go there yet," she said of bulletproof backpacks. "I absolutely thought I would never go there, either, then you change the way you think about everything," Alhadeff said. "It's something to protect themselves if everything fails."