More than 4 million children endured lockdowns last school year, a groundbreaking Washington Post analysis found. The experience left many traumatized.

Locked behind their green classroom door, MaKenzie Woody and 25 other first-graders huddled in the darkness. She sat on the vinyl tile floor against a far wall, beneath a taped-up list of phrases the kids were encouraged to say to each other: “I like you,” “You’re a rainbow,” “Are you ok?”

In that moment, though, the 6-year-old didn’t say anything at all, because she believed that a man with a gun was stalking the hallways of her school in the nation’s capital, and MaKenzie feared what he might do to her.

Three times between September and November, bursts of gunfire near MaKenzie’s public charter elementary school led DC Prep to seal off its Southeast Washington campus and sequester its students. During the last one, on Nov. 16, a silver sedan parked just around the corner at 10:42 a.m., then the men inside stepped out and fired more than 40 rounds. As MaKenzie’s class hid upstairs, teachers frantically rushed three dozen preschoolers off the playground and back into the building.

“The lockdowns,” as MaKenzie calls them, have changed her, because the little girl with long braids and chocolate-brown eyes remembers what it was like before them, when she always felt safe at her Anacostia school, and she knows what it’s been like afterward, when that feeling disappeared.

School shootings remain rare, even after 2018, a year of historic carnage on K-12 campuses. What’s not rare are lockdowns, which have become a hallmark of American education and a byproduct of this country’s inability to curb its gun violence epidemic. Lockdowns save lives during real attacks, but even when there is no gunman stalking the hallways, the procedures can inflict immense psychological damage on children convinced that they’re in danger. And the number of kids who have experienced these ordeals is extraordinary.