INDIANAPOLIS (AP) _ Ten-year-old Rachella Bryant bounded off the school bus, braids bobbing, Tweety Bird backpack swinging from the crook of her arm. Then she held still as police officers with metal detectors checked her to make sure she wasn't packing a gun or a knife.

In mid-April, Indianapolis became what is believed to be the only district in the nation to screen elementary school pupils for weapons. Not even big cities such as New York, Los Angeles, Chicago and Miami have taken such a step.

The move was prompted by the recent arrests of three children who brought guns to school, school officials said.

Superintendent Duncan Pat Pritchett said the new policy is necessary to protect students, teachers and staff.

``It's a sad situation, but at the same time it made me feel good from the standpoint that we know that the issue is out there because we've seen it in our schools,'' he said. ``At least we're taking a stand that says we're not going to tolerate it anymore.''

School violence experts are wondering why a mid-sized Midwestern city with a public school enrollment of about 45,000 has adopted a tactic often reserved for major metropolitan-area junior high and high schools.

The New York City school system, the nation's largest with nearly 1.1 million students, has reported only two cases this year of elementary school youngsters bringing guns to school. Other major school systems also said that such incidents are rare and that they see no need for screening.

``I can imagine that folks there (Indianapolis) would think three kids bringing guns to school would be pretty spooky,'' said Dennis Kenney, research director for the Police Executive Research Forum, a police think tank.

For seven years, Indianapolis had been using metal detectors in its junior and senior high schools only, until a 8-year-old boy was arrested in March for bringing a loaded gun to school to protect himself from a 10-year-old. Two other children who brought guns to school earlier this year were also arrested.

Under the new program, two or three of the city's 62 elementary schools are screened each week. The schools are chosen by lottery, and the students are selected at random. As of Monday, no guns had been found.

Rachella giggled with her friends as they walked into Public School 82, where students from Bus 30 had been selected for screening.

``The detector's going to go off on me,'' Rachella said. ``I've got change in my pockets, and my keys. I like making metal detectors go off, especially in the airport.''

She stood tall _ chin up, arms outstretched, feet apart _ waiting for the detector to beep. It did. She smiled. But no guns. No knives.

``A lot of kids grow up in violent neighborhoods,'' said police Lt. John Stiegelmeyer. ``It's extreme, but we'd rather be proactive, than reactive.''

But Kenney said random checks don't work because too many kids can slip through. And he said few shootings happen within the school walls.

``It's probably overkill,'' Kenney said of Indianapolis' policy.

Norm Black, a fifth-grade teacher at School 82, isn't so sure.

``I think it's a necessity,'' said Black, who has taught at the school for 10 years. ``When I started teaching, I never thought in a hundred years we'd have metal detectors in elementary schools. But I think in this day and age, we're exposed to so much violence. We don't handle conflict well.''

Fourth-grader Cherelle Lowe said she was scared when she heard that a student had brought a gun to her school. ``This is a good thing,'' she said of the metal detectors. ``That way, people understand not to bring guns to school.''

Kenneth S. Trump, president and chief executive of Cleveland-based National School Safety and Security Services, said schools should teach students how to keep conflicts from turning violent _ ``but we need a reasonably secure environment to do that.''

``Your 9 o'clock conflict resolution class doesn't do much good when a kid gets shot at 8 o'clock,'' he said.