Montgomery County police have arrested seven juveniles in connection with the alleged manufacture and sale of small pipe bombs at Western Junior High School in Bethesda.

Police said they also confiscated six pipe bombs, and, although the largest was only about five inches long, each would be sufficiently powerful to cause serious injury or death. Evidence collected so far, police said, indicates that the youths weren't fully aware of the bombs' potential destructive force.

All of those arrested are students at Western Junior High School, 5501 Massachusetts Ave., police said.

On Thursday, county, state and federal law enforcement officers took a search warrant to the home of one of the juveniles in the Brookmont area and confiscated the bombs and fragments of some that had already been detonated, according to Cpl. William Cleveland of the county police.

Also seized were firecrackers, empty military rifle shell casings and model rocket engine fuel, which police said were used in making the bombs.

A 14-year-old and a 15-year-old were each charged with two counts of manufacturing and selling explosive devices without a license and two counts of possession of an explosive device, according to the police report.

Five other youths, who police said were "younger than 14," were each charged with possession of an explosive device. Police said at least 16 pipe bombs had been sold to the five.

All seven youths were released in the custody of their parents pending disposition of the cases by juvenile authorities.

Cleveland said the youths who are charged "seemed to think it was kid stuff." The two accused of selling the bombs were offering them for from 35 to 85 cents apiece, he said.

Police said one of the alleged pipe bomb sales occurred aboard a school bus headed for Western.

Joseph Valani, Western vice principal, and none of the seven students was a troublemaker. "They're really kind of babes in the woods," he said. "They seemed to think (having pipe bombs) was a game. I think they just saw them as giant firecrackers."

An investigation began Tuesday when a science teacher at the school found three pipe bombs in a jacket a ninth grade student had accidentally left behind after school, police and Valani said. The teacher brought the jacket to Valani, who questioned the student when he returned for the jacket.

The student told Valani he had purchased the bombs from a 15-year-old, according to police. Investigators said they learned the 15-year-old was making pipe bombs at his home, using pieces from a coil of copper tubing that police found in a field near the home, and selling them at school.

The 14-year-old charged with making and selling bombs told police he had learned the manufacturing technique from the 15-year-old, police said.

A police spokesman said unauthorized possession of explosives is a federal as well as state offense. Adults found guilty of the offense can be sentenced to up to 10 years in prison.

However, the spokesman said, disposition of the charges against the youths will depend on the findings of the county juvenile authorities.

Cpl. Phillip B. Caswell, head of the Montgomery Police Department's media services section, said that although the arrests were made Thursday, they weren't publicly disclosed until yesterday because "all the facts weren't clear."