MIAMI (AP) — The nation's largest gun-rights lobby called Friday for the placement of an armed police officer in every school, but parents and educators questioned how safe such a move would keep kids, whether it would be economically feasible and how it would alter student life. Their reactions ranged from supportive to disgusted.

Already, there are an estimated 10,000 sworn officers serving in schools around the country, most of them armed and employed by local police departments, according to a membership association for the officers. Still, they're deployed at only a fraction of the country's approximately 98,000 public schools, and their numbers have declined during the economic downturn. Some departments have increased police presence at schools since last week's shooting rampage at a Connecticut elementary school that left 26 dead, but say they can only do so temporarily because of funding.

The National Rifle Association said at a news conference that it wants Congress to fund armed officersin every American school, breaking its silence on the Connecticut shootings. The idea made sense to some anxious parents and teachers, but provoked outright anger in others.

"Their solution to resolve the issue around guns is to put more guns in the equation?" said Superintendent Hank Grishman of the Jericho, N.Y., schools on Long Island, who has been an educator for 44 years. "If anything it would be less safe for kids. You would be putting them in the midst of potentially more gunfire."

Where school resource officers are already in place, they help foster connections between the schools and police, and often develop a close enough relationship with parents and children that they feel comfortable coming forward with information that could prevent a threat, said Mo Canady, executive director of the National Association of School Resource Officers.

But an Oklahoma educator who teaches at a school with armed officers described the NRA's proposal as a "false solution," though she's not opposed to the presence of more police.

"I teach at a school that has four armed police officers on campus every day, but it's more than a quarter of a mile from the main office to my room, and I'm not even the farthest room away," said Elise Robillard, a French teacher at Westmoore High School. "If (a student) put a loaded gun in their bag and came to my classroom and pulled it out and started shooting, by the time the police officer figured out what was going on and got to my classroom, we'd all be dead. This whole hallway could be dead before a policeman got here."

Around the country, school systems sometimes rotate armed officers through schools or supplement them with unarmed safety agents. New York City's school district is the largest in the country with more than 1 million students. The NYPD has 350 armed officers who rotate throughout the school system, and they're supplemented by unarmed safety personnel who also report to the department. In Philadelphia, school officials have rejected armed patrols in city schools and instead use unarmed school police.

In rural Blount County, Ala., a tobacco tax is used to fund a squad of nine armed sheriff's deputies and a supervisor who are assigned to work inside the system's 16 schools on a full-time basis, superintendent Jim Carr said Friday. They also assist in sports games and other after-school events.

An armed sheriff's deputy assigned to Columbine High School the day of the massacre there in 1999 was unable to stop the violence, though police procedures around the country have changed since then.

According to a Jefferson County Sheriff's Department report released in 2000, the uniformed sheriff's deputy was eating lunch in his patrol car at a park near the school when he rushed to the school in response to a radio report about the violence. The deputy briefly exchanged fire with one of the gunmen, but the gunman ran back inside the building to continue the rampage.

The officer radioed for assistance, and police followed the then-standard procedure of waiting for a SWAT team to arrive before entering the building. Since that tragedy, police procedures have been changed to call for responding officers to rush toward gunfire to stop a gunman first.

In his speech, NRA chief executive officer Wayne LaPierre said Congress should appropriate funds to post an armed police officer in every school. In the meantime, he said the NRA would develop a school emergency response program that would include volunteers from the group's 4.3 million members to help guard children.

The NRA's call came two days after a Kentucky county sheriff announced on Facebook that deputies would have an increased school presence beginning in January. The announcement was met with dozens of notes of thanks and positive comments from parents.

"Thank you so very much," wrote one commenter. "I can stop stressing a little while at work now."

"This is the best news we could have received for Christmas!" wrote another.

Monte Evans, a sixth grade teacher in Wichita, Kan., said schools should have a designated point person licensed and trained to shoot a gun.

"What am I going to stop them with? A stapler?" said Evans, an NRA member. "You need equal force."

Rose Davis, 47, who lives in Chicago's South Side Englewood neighborhood and helps care for her two young grandchildren, said she supports the idea of having armed police officers in schools. Her neighborhood is beset by gang violence and she worries about it spilling into schools.

"With the things going on today, you really don't feel secure," she said.

Even those who support the proposal, however, questioned how practical it would be.

"The real question is sustainability," said Ken Trump, president of the Cleveland-based consulting firm National School Safety and Security Services. "In the long haul, how are you going to fund that?"

But Randi Weingarten, president of the American Federation of Teachers, one of the nation's largest teachers' unions, called the NRA's idea "irresponsible and dangerous."

"Schools must be safe sanctuaries, not armed fortresses," she said.

Republican New Jersey Gov. Chris Christie said that posting armed guards outside schools wouldn't make classrooms safer or encourage learning.

"You can't make this (school) an armed camp for kids," he said.

Jacina Haro, a college educator from Malden, Mass., and the mother of two young children said the solution shouldn't be about having more weapons on campus.

"Schools shouldn't be about guns," said the 38-year-old. "It should be a safe place to learn, free from weapons and the like. I understand wanting to protect our children, but I don't know if that's the right solution. It's a scary solution."

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Associated Press writers Frank Eltman in Mineola, N.Y.; Maryclaire Dale in Philadelphia; Barbara Rodriguez in Des Moines, Iowa; Jason Keyser in Chicago, Sean Murphy, Oklahoma City; Colleen long in New York; Colleen Slevin in Denver and Jay Reeves in Birmingham, Ala., contributed to this report.

FILE - This undated photo shows Adam Lanza in a Newtown High School yearbook photo. Authorities have identified Lanza as the gunman opened fire Friday, Dec. 14, 2012, inside an elementary school in Newtown, Conn., killing 26 people, including 20 children, before killing himself. People figure there surely were signs of impending violence. But experts say predicting who will be the next mass shooter is virtually impossible _ partly because as commonplace as these calamities seem, they are relatively rare crimes. Still, a combination of risk factors in troubled kids or adults including drug use and easy access to guns can increase the likelihood of violence, experts say. (AP Photo)

FILE - In this July 23, 2012 file photo, James E. Holmes appears in Arapahoe County District Court in Centennial, Colo. Holmes was being held on suspicion of first-degree murder, and facing additional counts of aggravated assault and weapons violations stemming from a mass shooting in a movie theater in Aurora, Colo., that killed 12 and injured dozens of others. People figure there surely were signs of impending violence. But experts say predicting who will be the next mass shooter is virtually impossible _ partly because as commonplace as these calamities seem, they are relatively rare crimes. Still, a combination of risk factors in troubled kids or adults including drug use and easy access to guns can increase the likelihood of violence, experts say. (AP Photo/Denver Post, RJ Sangosti, Pool, File)

CHICAGO (AP) — It happened after Columbine, Virginia Tech, Aurora, Colo., and now Sandy Hook: People figure there surely were signs of impending violence. But experts say predicting who will be the next mass shooter is virtually impossible — partly because as commonplace as these calamities seem, they are relatively rare crimes.

Still, a combination of risk factors in troubled kids or adults including drug use and easy access to guns can increase the likelihood of violence, experts say.

But warning signs "only become crystal clear in the aftermath, saidJames Alan Fox, a Northeastern University criminology professor who has studied and written about mass killings.

"They're yellow flags. They only become red flags once the blood is spilled," he said.

Whether 20-year-old Adam Lanza, who used his mother's guns to kill her and then 20 children and six adults at their Connecticut school, made any hints about his plans isn't publicly known.

Fox said that sometimes, in the days, weeks or months preceding their crimes, mass murderers voice threats, or hints, either verbally or in writing, things like "'don't come to school tomorrow,'" or "'they're going to be sorry for mistreating me.'" Some prepare by target practicing, and plan their clothing "as well as their arsenal." (Police said Lanza went to shooting ranges with his mother in the past but not in the last six months.)

Although words might indicate a grudge, they don't necessarily mean violence will follow. And, of course, most who threaten never act, Fox said.

Even so, experts say threats of violence from troubled teens and young adults should be taken seriously and parents should attempt to get them a mental health evaluation and treatment if needed.

"In general, the police are unlikely to be able to do anything unless and until a crime has been committed," said Dr. Paul Appelbaum, a Columbia University professor of psychiatry, medicine and law. "Calling the police to confront a troubled teen has often led to tragedy."

The American Academy of Child & Adolescent Psychiatry says violent behavior should not be dismissed as "just a phase they're going through."

In a guidelines for families, the academy lists several risk factors for violence, including:

—Previous violent or aggressive behavior

—Being a victim of physical or sexual abuse

—Guns in the home

—Use of drugs or alcohol

—Brain damage from a head injury

Those with several of these risk factors should be evaluated by a mental health expert if they also show certain behaviors, including intense anger, frequent temper outbursts, extreme irritability or impulsiveness, the academy says. They may be more likely than others to become violent, although that doesn't mean they're at risk for the kind of violence that happened in Newtown, Conn.

Lanza, the Connecticut shooter, was socially withdrawn and awkward, and has been said to have had Asperger's disorder, a mild form of autism that has no clear connection with violence.

Autism experts and advocacy groups have complained that Asperger's is being unfairly blamed for the shootings, and say people with the disorder are much more likely to be victims of bullying and violence by others.

According to a research review published this year in Annals of General Psychiatry, most people with Asperger's who commit violent crimes have serious, often undiagnosed mental problems. That includes bipolar disorder, depression and personality disorders. It's not publicly known if Lanza had any of these, which in severe cases can include delusions and other psychotic symptoms.

Young adulthood is when psychotic illnesses typically emerge, and Appelbaum said there are several signs that a troubled teen or young adult might be heading in that direction: isolating themselves from friends and peers, spending long periods alone in their rooms, plummeting grades if they're still in school and expressing disturbing thoughts or fears that others are trying to hurt them.

Appelbaum said the most agonizing calls he gets are from parents whose children are descending into severe mental illness but who deny they are sick and refuse to go for treatment.

And in the case of adults, forcing them into treatment is difficult and dependent on laws that vary by state.

All states have laws that allow some form of court-ordered treatment, typically in a hospital for people considered a danger to themselves or others. Connecticut is among a handful with no option for court-ordered treatment in a less restrictive community setting, said Kristina Ragosta, an attorney with the Treatment Advocacy Center, a national group that advocates better access to mental health treatment.

Lanza's medical records haven't been publicly disclosed and authorities haven't said if it is known what type of treatment his family may have sought for him. Lanza killed himself at the school.

Jennifer Hoff of Mission Viejo, Calif. has a 19-year-old bipolar son who has had hallucinations, delusions and violent behavior for years. When he was younger and threatened to harm himself, she'd call 911 and leave the door unlocked for paramedics, who'd take him to a hospital for inpatient mental care.

Now that he's an adult, she said he has refused medication, left home, and authorities have indicated he can't be forced into treatment unless he harms himself — or commits a violent crime and is imprisoned. Hoff thinks prison is where he's headed — he's in jail, charged in an unarmed bank robbery.

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Online:

American Academy of Child & Adolescent Psychiatry: http://www.aacap.org

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AP Medical Writer Lindsey Tanner can be reached at http://www.twitter.com/LindseyTanner