President Donald Trump has called for the arming of qualified teachers in the wake of a deadly shooting that left 17 people dead at a Florida high school, but in Texas dozens of school districts already allow staff members to carry firearms.

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Officials with the Texas Association of School Boards on Thursday told KSAT that they were aware of at least 172 school districts that let staff members carry firearms. Each district individually decides whether to allow staff to carry weapons, board spokeswoman Theresa Gage told the news station.

Under state and federal laws, schools are usually considered gun-free zones, but Texas law allows for districts to authorize employees to carry firearms under a pair of programs, the Corpus Christi Caller-Times reported.

The Guardian Plan, which allows for certain teachers to be designated as "guardians" who are allowed to carry concealed handguns, was created in 2007 as schools were reeling in the wake of a shooting at Virginia Tech that left more than 30 people dead and nearly two dozen injured, Texas Monthly magazine reported in 2014.

Four years after the creation of the Guardian Plan, the state legislature passed the Protection of Texas Children Act. The act allows school districts to arm and train one employee as a school marshal for every 400 students, according to Texas Monthly.

Agua Dulce Independent School District Superintendent Wayne Kelly told the Caller-Times that his district chose to participate in the Guardian Plan starting in 2016. To participate in the program, teachers and staff members are required to undergo mental health evaluations and 80 hours of training by the Texas Commission on Law Enforcement, according to the newspaper.

"I feel like it would be good because there's a way to stop (school shooters)" under the Guardian and the School Marshal plans, Fabian Crossland, whose son is a kindergartner, told KSAT.

Still, the plans have their critics, including Texas State Teachers Association spokesman Clay Robison.

"It's a bad idea. It's always been a bad idea, and it will stay a bad idea," Robison told the Dallas Morning News. "Teachers are there to teach, and they will protect their kids as the teachers did their best to do in Florida. Steps need to be taken to reduce the number of guns floating around in the hands of wrong people. Guns in the hands of teachers are not the solution. It's a cop-out."

Trump on Friday reiterated his call to allow certain teachers and school administrators to carry concealed weapons in school, arguing that such a move would prevent or drastically cut down on the carnage caused by school shootings.

He wrote Thursday on Twitter, “If a potential ‘sicko shooter’ knows that a school has a large number of very weapons talented teachers (and others) who will be instantly shooting, the sicko will NEVER attack that school.”

“Why do we protect our airports, our banks, our government buildings, but not our school?” Trump asked Friday during a speech at the Conservative Political Action Conference in Maryland. “Our schools are essentially gun-free zones and that makes them very dangerous places.”

According to the Los Angeles Times, schools currently allow staff members to carry guns on campuses in about two dozen states.