A nonprofit's intense new public service announcement depicting children in a school shooting reflects public fears on the subject that are out of step with the rareness of violence in schools.

Sandy Hook Promise's PSA "Back to School Essentials" debuted Wednesday, showing students using typical items for survival as a shooting takes place. A girl makes her sock into a tourniquet for a wounded classmate. A boy uses his new skateboard to break a window and escape. It ends with a girl cowering in a bathroom, tearfully texting her mother as the shooter approaches.

The disturbing spot reflects the anxieties of parents and students alike. A 2018 survey conducted by the Pew Research Center found 57 percent of U.S. teens, including majorities of both boys and girls, are either "very" or "somewhat" worried that a shooting could happen at their school.

An even higher proportion, 63 percent, of those teens' parents express the same worry. This represents a substantial increase over a 2017 study, which found 36 percent of parents thought it "highly likely" their local high school would experience a "gun incident" in the next three years.

These anxieties, however, seem out of proportion to the numbers.

According to the Centers for Disease Control, the average rate of multiple-victim school-associated homicides between 1994 and 2017 was about one in 12.5 million. In 2018, there were 55 gun-violence deaths in schools—a number which, while lamentable, is roughly on par with the historical average for lightning strike deaths. Fifty-five may be an overcount, as such estimates tend to rely on a fairly broad definition of school shooting—narrower, more intuitive measures put the true number even lower.

Recent research suggests that schools have been getting safer. A report from Northeastern University found that the rate of students killed today is roughly a quarter of what it was in the 1990s. That is in line with a report from the Bureau of Justice Statistics, which found rates of violent victimization, theft, and self-reported fear in schools have all declined substantially since the 1990s.

The PSA received substantial media attention. It was shown partially or entirely at least nine times Wednesday and Thursday on MSNBC and NBC, including on Today and NBC Nightly News. CNN and HLN aired it at least five times, and the ad was also covered on CBS Evening News.

Hosts added their own commentary for the ad, which aired as the gun control debate has reignited in the wake of mass shootings last month in Texas and Ohio.

After airing the PSA, MSNBC host Nicolle Wallace stared into the camera for a moment before saying, "If that made you uncomfortable, that was the point. Children as young as three have active-shooter drills in schools."

MSNBC host Andrea Mitchell said it demonstrated the "harrowing new reality that students face at schools across the country."

Several Democratic presidential candidates, including Sen. Kamala Harris (Calif.), South Bend mayor Pete Buttigieg, and Andrew Yang, shared the PSA on Twitter.

Sandy Hook Promise was founded out of the Sandy Hook Elementary School massacre on Dec. 14, 2012, where 26 people were murdered by a lone gunman. Twenty of the victims were young children.

"We don't want people to turn away from it, so pretending it doesn't exist is not helping to solve it," Sandy Hook parent Nicole Hockley told Today.

The ad promotes the group's "Know the Signs" campaign, which teaches students and teachers how to identify warning signs of a potential shooter in their midst and potentially intervene.