The moment she heard the first pops of gunfire, the teacher knew what she had to do: She needed to make sure that her classroom door was locked.
But at Robb Elementary School in Uvalde, Texas, that seemingly simple task would require her to take a life-threatening risk.
As most of her students crawled under their desks to take cover, she made eye contact with one child she had always given the same job during their lockdown drills, the teacher recalled in an interview. Without speaking, the student followed her to the classroom door.
“Do you remember what we do?” the teacher asked the boy, trying to keep her voice calm.
The boy, with tears in his eyes, nodded and said, “Yes, ma’am.”
Then the teacher pulled the door open. Took a deep breath. And stepped into the hall, praying that the shooter wouldn’t see her.
The Robb Elementary teacher and her colleagues had been instructed to keep their classroom doors closed and locked at all times, using keys that they were required to carry with them, she said. But that system created frequent opportunities for mistakes: Each time she and her class returned from lunch or from the bathroom, she said, she had to use her key to unlock the door handle — and hope that she remembered to relock it again before going back inside.
Once she was inside, the teacher said, there was no way to confirm whether the exterior handle was locked.
To remove any doubt, she came up with a system for the lockdown drills. Anytime an alarm sounded, she would step into the hall and pull the classroom door shut, then test the exterior handle to make sure it was locked and latching correctly. The student she had deputized to follow her to the door would then let her back inside.
But this time it wasn’t a drill, and she was terrified.
After exiting her class, the teacher quickly pulled the door shut and wiggled the exterior handle, confirming it was locked. As she waited for her student to let her back inside, she recalled hearing more gunshots — and footsteps.
“I was in the hallway with him,” she said of the gunman.
Then, her student pulled the door open, just as they’d practiced. She darted back into the classroom, pushed the door closed and they joined the other students hiding on the floor.
Moments later, the gunman entered a classroom across the hall — just steps away from where she’d been standing — and opened fire.
Moving toward gunfire was the only way she could be certain that her students were safe, the teacher said. That’s because Robb Elementary is among thousands of schools across the country lacking a basic safety feature that experts have recommended for decades: classroom doors that lock from the inside.
Despite billions of dollars that have been poured into hardening schools nationally, 1 in 4 U.S. public schools lack classroom doors that can be locked from the inside, according to a survey conducted two years ago by the National Center on Education Statistics, a federal research office.
The safety feature is missing in much of Texas: 36% of the state’s schools said they did not have interior-locking doors in the majority of their classrooms, according to a 2018 survey commissioned by Gov. Greg Abbott. Outdated locks are especially common in older school buildings that haven’t been renovated, industry representatives said.
Built in the 1960s, Robb Elementary had classroom doors that could only be locked and unlocked from the outside, according to state authorities and the teacher. She spoke to NBC News on the condition that she not be named, because she is not ready to talk publicly about her experiences on May 24, when a gunman opened fire inside a pair of conjoined classrooms, killing 19 children and two teachers.
Doors that can be quickly and easily locked can mean the difference between life and death when a shooter is on school grounds. That’s why post-shooting safety commissions, teachers, fire safety groups and both gun rights and gun control groups have all advocated for interior-locking doors since the Columbine shooting in 1999, in which two students killed 12 classmates and one teacher.
No state requires all schools to install interior locks, though some recommend it, and a wave of school security grants often follows shootings. But even when they have new funds available, schools have struggled to decide what to prioritize.
“School districts and administrators get overwhelmed with numbers of options and solutions,” said Cedric Calhoun, chief executive officer of DHI, an industry group for door security professionals. “A lot of times they can overlook the simplicity of a door lock.”