Gun-rights advocates in Utah have trained 200 teachers how to handle concealed weapons in the latest effort to confront school assailants.
The course follows the murder of 20 children and six staff at Sandy Hook Elementary School in Newtown, Connecticut.
English teacher Kevin Leatherbarrow, who holds a licence to carry a concealed weapon, says he does not see anything wrong with arming teachers in the aftermath of the school shooting.
"We're sitting ducks," said Mr Leatherbarrow, who works at a Utah charter school. "You don't have a chance in hell. You're dead - no ifs, ands or buts."
In Ohio, a firearms group said it was launching a test programme in tactical firearms training for 24 teachers.
The Arizona attorney general is proposing a change to state law to allow an educator in each school to carry a gun.
The moves come after the National Rifle Association proposed placing an armed officer at every US school.
Some education officials say they believe it is dangerous to allow guns in schools, suggesting teachers could be overpowered by an assailant, or that students could get hold of firearms and accidentally or deliberatley shoot classmates.
"It's a terrible idea," said Carol Lear, a chief lawyer for the Utah Office of Education. "It's a horrible, terrible, no-good, rotten idea."
Utah educators say they would ban guns if they could, but legislators left them with no choice. State law forbids schools, districts or college campuses from imposing their own gun restrictions.
Educators say they have no way of knowing how many teachers are armed. Gun-rights advocates estimate 1% of Utah teachers, some 240, are licensed to carry concealed weapons. It is not known how many do so at school.
Pro-guns activists say teachers can act more quickly than law enforcement in the critical first few minutes to protect children from the kind of deadly shooting that took place in Connecticut.
The free firearm instruction - which involves using plastic weapons - emphasises the need for people who are facing deadly threats to announce they have a gun and retreat or take cover before trying to shoot, said Clark Aposhian, chairman of the Utah Shooting Sports Council, the state's leading gun lobby.
"I just bought a bra holster," said Jessica Fiveash, a 32-year-old Utah teacher and wife of a retired Army sergeant who grew up shooting and said she had no hesitation packing a gun at school.
Mr Leatherbarrow said he often felt threatened while working at an inner-city school in Buffalo, New York, where he got a licence to carry a pistol. He moved less than a year ago to Utah, where he feels safer.
But he said gun violence can break out anywhere. He said he was highly trained in handling guns - and was taking criticism from parents who do not appreciate his views on school safety.
"I'm in agreement not everybody should be carrying firearms in school. They're not trained. But for some parents to think we're cowboys, that frustrates me," he said. "I wish parents would understand."