A seventh-grade student at Jefferson Junior High School in Southwest Washington was arrested yesterday morning and charged with a weapons violation after school officials confiscated a loaded handgun from his book bag, D.C. police and school officials reported.

They said the 13-year-old youth, whose name was not released, was charged with carrying a pistol without a license, which for first-time offenders is a misdemeanor. Police said the handgun was a .38 caliber FNH semiautomatic loaded with a clip containing four rounds. The student had eight other bullets in his pocket, police said.

Police will test the gun to determine whether it is operable, police spokesman William White III said.

The incident was the second involving a handgun in a District school in less than two weeks, according to Janis Cromer, spokeswoman for the school system. On Oct. 21, two Spingarn High School students were shot, but not seriously wounded, in a crowded gymnasium during a quarrel over a radio.

"I don't think it's a pattern in that these incidents are unrelated, but certainly the number of incidents is out of the ordinary and alarming," Cromer said. "Two in a matter of weeks is enough to give us a lot of concern."

According to Cromer, a teacher saw the youth and two other students "huddled around" in a first-floor hallway of the school, at 836 H St. SW, about 10 a.m. The gathering "aroused suspicion enough for the teacher to detain" the student, according to Cromer.

It was unclear, Cromer said, if the teacher had seen the gun or if the youth produced it when questioned about the contents of his book bag.

Police said two small racing cars, a paddle ball and other toys also were in the bag.

According to Vera White, principal of Jefferson, the youth "said he had picked up a gun out of the trash can in front of his house," though Cromer said that later in the day the youth refused to answer questions about where he obtained the pistol.

Police spokesman White said that the youth's parents will be interviewed "to provide us with any information they may possess" about the weapon. He said a background check and tests will be conducted to determine whether the gun has been used in any crime and if it is registered.

White said that the youth was referred to the juvenile division of D.C. Superior Court. It could not be learned last night if he had been returned to the custody of his parents or if he was being detained.

School spokeswoman Cromer said the youth has been placed on a "major suspension," which can last for up to 10 days.

She said the principal at Jefferson will decided what additional action to take, if any, after meeting with the youth's parents.

"Usually our problem has been with outsiders and adults coming into the schools, and that's where we've focused much of our attention," Cromer said, by taking such steps as having security aides roam the halls and requiring visitors to wear identification badges.

She said other school systems will be consulted to see how they deal with the gun problem.

In Detroit, students pass through metal detectors before entering a school building. Cromer said that she is not sure that would be feasible in the District.