After Uvalde, a kindergarten teacher trains to carry a weapon at school

At Sandy Hook Elementary in Newtown, Connecticut, in 2012, the first 911 call was made after about five minutes and the first officers arrived at the school less than four minutes later. Yet 20 children and six adults were killed. In Parkland, Florida, the shooter killed 17 people in just under six minutes.

Even in Uvalde, where police were criticized for waiting on the spot for more than an hour, the gunman allegedly fired more than 100 shots in the first three minutes, according to a state report.

“Time is all that matters,” Mr. Irvine said. “It’s so simple.”

Of the eight school employees in training, Mandi was in some ways an anomaly. She was the only woman in the group. Several others were administrators – a superintendent, a principal – rather than teachers.

In other ways, she was typical.

Everyone was comfortable with firearms. Mandi described hunting with her husband and shooting at a weekend shooting range. She said she had taken other firearms courses, including concealed carry training, one of the prerequisites for participating in FASTER.

Like others, she worked in a rural area, where carrying guns in schools is more common, in part because of slower police response times. One group in the formation, from Oklahoma, estimated the response time in their area to be at least 22 minutes.

“The last thing I want is for people to think we’re just a bunch of teachers throwing guns and wanting an excuse to carry guns into schools,” he said. Mark, an Ohio middle school teacher who described his school’s hallway measurement to determine how far he should learn to shoot.