The team was vetted by Mr. Scheu and Sheriff Lenhart, and completed a 16-hour training course that includes firearm safety, unarmed defensive tactics and basic gunshot first aid. Its members are required to attend a concealed weapons course, as well as additional monthly trainings at either the firing range where they practice marksmanship and in school-based simulations where they practice in the hallways, identifying threats and eliminating them with air guns.

Since the team was created, it has responded to one incident, this past August when a student brought a gun to school in his backpack. It did not require a member to retrieve a gun.

The measures here met some opposition at first, from the town’s teachers union and police chief, who were concerned about gun safety.

But Rick Cron, the armed guard at Sidney Middle School, said he would put members of his team up against any law enforcement officer in Ohio. The state requires that officers fire 25 bullets a year; his team members shoot at least 600.

“It’s the teacher’s responsibility to protect the kids, no matter what, and they do it already,” Mr. Cron said, “but without the tools.”

Nicki New, the parent of three students in Sidney City Schools, said she felt safer dropping off her children knowing there were staff members equipped to respond to a parent’s worst nightmare.

“God forbid, if something would happen, knowing that not only a law enforcement officer is there, but there are teachers in that building who can give my child a fighting chance, is even more reassuring,” Ms. New said.