Arkansas school districts can't use a little-known state law to employ teachers and staff as guards who can carry guns on campus, the state's attorney general said Thursday in an opinion that likely ends a district's plan to arm more than 20 employees when school starts later this year.

Attorney General Dustin McDaniel, a Democrat, wrote in a legal opinion issued by his office that a state board that licenses private security agencies didn't have the authority to allow districts to employ their teachers and staff as security guards. A state lawmaker requested the opinion a day after The Associated Press reported on a plan by the Clarksville School District in western Arkansas to use more than 20 teachers and staff as volunteer security guards armed with concealed 9 mm handguns.

"Simply put, the code in my opinion does not authorize either licensing a school district as a guard company or classifying it as a private business authorized to employ its own teachers as armed guards," McDaniel wrote.

David Hopkins, Clarksville's superintendent, said he had spoken with McDaniel earlier Thursday about the opinion. Hopkins said he was still reviewing the opinion but that "it sounds like he's saying that we can't do the program."

"Obviously we're going to comply with the law. We're not going to break the law," said Hopkins, who had appeared on NBC's "Today" show Thursday morning to tout the program. "We wanted to provide the training and give the sense of a secure place for our parents and students. I tell you, this has really thrown a monkey wrench into it."

The idea of arming schoolhouses against gunmen was hotly debated across the country after the school shooting in Connecticut last December that left 20 children and six teachers dead. The National Rifle Association declared it the best response to serious threats. But even in the most conservative states, most proposals faltered in the face of resistance from educators or warnings from insurance companies that schools would face higher premiums.

Participants in Clarksville's program are given a one-time $1,100 stipend to purchase a handgun and holster. Hopkins said the district is paying about $50,000 for ammunition and for training by Nighthawk Custom Training Academy, a private training facility in northwest Arkansas.

The 53-hour training program included roleplaying drills of school shootings, with teachers and staff using "airsoft" pellet guns, with students wearing protective facemasks and jackets.

The Lake Hamilton School District has been using the same law for years to train a handful of administrators as security guards, but the guns are locked away and not carried by the administrators during the school day.

Lake Hamilton Superintendent Steve Anderson said he was talking with local prosecutors, school attorneys and other officials about how to proceed. Anderson said the district has had its license for 25 years.

"We'll take appropriate measures and I imagine this is something that will eventually be settled in a court of law or the Legislature," Anderson said.

Bill Sadler, a spokesman for Arkansas State Police, said pending applications by two or three districts for similar licenses have been put on hold because of McDaniel's opinion. Later Thursday, Sadler said any pending applications for entities or businesses that aren't security companies were also on hold.

Sadler said it will be up to the licensing board on what to do with the 13 existing licenses.

"We've got to hear from the board what they want us to do with the existing licenses that are out there," Sadler said. "Until we hear that and get some clear guidance from the board, we're in a holding pattern"

McDaniel said his opinion wouldn't affect districts' ability to contract with private security companies or to use law enforcement as school resource officers. He also noted that the Legislature has the power to change the law prohibiting school employees from carrying guns on campus.

A House panel in February rejected a bill that would have allowed some school employees to carry concealed handguns on campus after completing a 40-hour course at a state law enforcement training academy.

McDaniel noted that the districts were seeking licenses under a provision of the law that applies to private security firms and guard companies.

"If a school district were indeed functioning as a `guard company,' then, it would be organized to provide services to any and all `customers' purely for the purpose of generating income -- a private business motivation that is self-evidently anathema to a school district's purely public functions," he wrote.