Callisburg, Texas (CNN) While the nation debates whether teachers should carry guns to protect students from armed intruders, the question's already settled in one Texas school district, where educators have had firearms on campus for years.

And while no teacher in Callisburg, Texas, has been called on yet to fire a weapon in defense of a classroom, students in the Callisburg Independent School District say they feel safer knowing their teachers can protect them if the unthinkable happens.

About four years ago the district, which is about 85 miles north of Dallas, started what's known as the "guardian" program: a small force of volunteer school staff allowed to carry a concealed firearm on school grounds, said school superintendent Steve Clugston.

"We'll do whatever's necessary to protect our kids and staff," Clugston told CNN. "We don't want to be at the mercy of somebody that's intent on doing harm."

Clugston says the school's guardian force completes active shooter scenario training once a year and routinely takes target practice at gun ranges. Signs in front of the schools warn visitors that some staff members are armed and "may use whatever force is necessary to protect our students."

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