It’s an idea that was unthinkable in the U.S. only a few years ago — arming teachers in the classroom.

Nine states now allow teachers to bring guns into schools.

Officials in one of those states are now training teachers to deal with an armed assault on their school.

CGTN’s Hendrik Sybrandy reports.

In Greeley, Colorado, 17 paper targets are positioned so school administrators and teachers can get training for firearms skills.

Chris Wallace is with Tactical Defense Institute, a company which runs intensive training programs, paid for by nonprofit groups, for educators who own guns.

“We’re training them for a very narrow mission, just to respond to an active killer. They’re actually volunteering to step up and basically risk their lives to save the lives of their students if there’s an attack,” Wallace said.

From Columbine to Sandy Hook, there’s been no shortage of gun incidents in U.S. schools in the past two decades. That’s prompted some U.S. states to allow teachers with gun permits to carry concealed weapons on school grounds, provided they’re also designated as school security officers.

“I know as a police officer I can’t be there all the time,” Police Officer and Instructor Graham Dunne said. “Even if I’m only a block away, by the time I get the call and I respond, three minutes has passed, it’s over with. So we need people on scene right then and there to protect the kids.”

“It’s been very eye-opening,” Ronnie Wilson, the school board president of Liberty Tree Academy said.

Over three days, Ronnie Wilson will learn how to handle and fire his weapon, when to use deadly force. And he’ll be taught about legal issues and proper medical response. He hopes to qualify for a course completion certificate, a key step he believes as he prepares to open up a new school.

“I would say that 100 percent of parents who have their child at a school would want to know that there is a crisis management plan in place,” Wilson said.

To qualify, students, school administrators and teachers are tested in 10 different scenarios–different distances from the target, various number of rounds fired as well as time to shoot.

Tom Mauser, who lost his son during the Columbine High School massacre in 1999, says because school shootings are still relatively rare, armed teachers are really unnecessary.

“It’s a bit overblown and quite a bit of an overreaction really. The likelihood of a very lightly trained person being able to respond effectively very, very small,” Mauser said.

In fact, he says, teachers with guns could make shooting events worse. But Wallace argues seconds count when an intruder with a weapon bursts into a school.

“Unfortunately, if you don’t have a person in that building, preferably several people in that building that can respond in real time to this, you are going to lose a lot more victims than you need to,” Wallace said.

Teachers are known for being highly protective of students and willing to defend them during a crisis. But is this the right approach Those enrolled in this course say yes.