School officials say arming teachers is the only way to protect the old brick schoolhouse, which sits 30 minutes from the nearest police station.
"How do you stop the angry person without enough sense?" said Superintendent David Thweatt of the Harrold Independent School District.
"It's not going to take very long for it to be a total massacre."
But critics say the risks of having guns around children far outweigh the potential threat of a crazed gunman.
"Which risk is more likely: that someone is going to accidentally set off a gun in class and God forbid hit a student, or someone will come in off the highway and start a random shooting spree?" said Doug Pennington, spokesman for the Brady Campaign to Prevent Gun Violence.
While random shootings grab headlines, they are extremely rare, Pennington said, adding that fewer than one percent of school-age homicide victims are killed on school grounds or on the way to and from school.
Pennington questioned whether teachers were adequately trained to respond in a crisis situation and said the school would be better off with a security guard -- the only people technically allowed to carry guns in Texas schools.
Thweatt would not say which teachers were armed or how many but said they all received adequate training.
Harrold's school board decided last October to allow its employees to carry concealed handguns on campus when the 2008-09 school year began on Monday.
Mass murders at schools, college campuses, shopping malls and churches have claimed scores of lives across the United States in recent years.
Some, like Harrold's superintendent, blame the violence on federal legislation enacted in 1995 that made such areas "gun-free zones."
"That's the place people could go if they are feeling crazy or mad at the world and get a big body count," Thweatt told AFP.
Thweatt says he studied the issue for two years while he filled his school with more than 100,000 dollars in state-of-the-art security systems.
But even with the new keyless entry, camera system, lock-down buttons and classroom telephones, Thweatt said he still could not have prevented a mass murder like the one in an Amish one-room schoolhouse in Pennsylvania in 2006 that left five girls dead.
It also would not have been enough to deter the deranged student at Virginia Tech University, who killed 32 people and wounded 23 in 2007.
"They were like fish in a barrel," Thweatt said.
The Harrold policy requires that each teacher who carries a gun be approved by its school board, earn a concealed carry license, and complete training in crisis management and hostage situations.
Guns must be worn -- not locked in a safe -- and loaded with ammunition designed to blast into powder instead of ricocheting through the hallways.
The decision to arm teachers isn't a far-fetched idea for this ranching community, said Bridget Knight, who lives in nearby Vernon.
"For Harrold, it makes total sense."
Its windswept fields are ranch country, she said, where guns are a mainstay -- if not to stop a madman, then to shoot a snake, a wild hog, a wild dog or coyote that might run onto the playground.
Even Harrold children are raised to handle guns, said Lee Anderson of nearby Wichita Falls, Texas.
"Most high school seniors been huntin' on their own since the age of 12," he said. Many eventually join the rodeo circuit or work in the oil fields.
"These are country people. They grow up with guns. It's nothing unusual."
Still, that doesn't make guns fit for the classroom, said Kristina Tirloni of the Texas Classroom Teachers Association.
She called the policy "extreme."
Adding security guard to a teacher's duties is "a lot of responsibility for someone who already has a lot of responsibility in the classroom," she said.
While a handful of colleges and universities allow people with permits to carry guns on campus, "as far as we are aware this is the first policy of its kind at the elementary or high school level," Pennington said.