When Edward Merrick was a kid, high school troublemakers would call in bomb scares when they wanted time off from class on warm spring days.

Merrick, now the police chief in Plainville, said he suspects a modern-day version of the bomb scare is sweeping area schools in the form of security lockdowns.

Students might be bringing bullets or spent shells onto to school property to cause a scare and shut down school for a while, he said.

Ammunition found recently at King Philip Middle School, Foxboro High School and Dighton-Rehoboth Regional High School forced officials to lock students in their classrooms for hours while the buildings were searched. The incidents at King Philip and Foxboro occurred within three days of each other last week.

Another bullet was found outside a Plainville elementary school, but it was discovered after school hours, so there was no lockdown. "It's like the bomb scares of the '60s and '70s. These are the new bomb scares," Merrick said.

But in an era following the 1999 mass shooting at Columbine High School in Colorado and a January stabbing at Lincoln-Sudbury High School in Massachusetts, Merrick said school officials cannot afford to treat the bullet findings lightly, even if they suspect there is no threat.

"Shame on us if we didn't do anything and something bad happens," he said.

Robert Gay, principal of North Attleboro High School and president of the Massachusetts Secondary School Administrators Association, takes a similar view.

He said school officials must err on the side of caution, even if it appears the local incidents are the work of "copycats" looking for attention.

"How do you explain to a parent if a child has been injured?" he said.

As a result, school gets disrupted, and the problem appears to be spreading.

He said the recent trouble reminds him of a series of bomb scares that were called in at high schools across the country after the Columbine shootings.

A security alternative is to install metal detectors, but Gay said: "I hope we don't have to go that route."

Gay said he suspects all the attention caused by a lockdown in one area school inspires students to do the same thing at their school. And, he said he wonders if the local media should avoid reporting on the incidents so that the offenders do not get the attention they crave.

One way to discourage the incidents is for students to see news stories about offenders being caught and punished, he said.

A photograph in The Sun Chronicle this week of two Foxboro students being arraigned in court for their role in a lockdown sends the right message, he said.

Kenneth Trump, president of National School Safety and Security Services, said school departments and the media have to balance attention given to the incidents with attention given to the consequences for those who caused the trouble.

"Those who consider copycat offenses need to hear not only about the disruptions, but about what happens when the offender is caught," he said.

He said lockdowns are becoming increasingly common because of all the security concerns schools have.

The lockdowns isolate students from what school officials believe could be a threat, he said.

Merrick said a regional group he is involved with called MetroWest Law Enforcement Council is offering to do security evaluations for schools and offer recommendations on how to respond to emergencies.

Meanwhile, Gay said he also hopes bringing bullets to school is a passing fad that will end when students start to realize a lockdown is no fun.

During a lockdown, students are typically locked in their classroom and the shades are drawn on the windows. They cannot leave until officials determine their is no danger.

The lockdown response to ammunition found at a school differs from the response to a bomb threat or fire alarm, in that students do not get to go outside and enjoy a warm spring day as they did in Merrick's time.