ANDOVER — High School Principal Peter Anderson wanted to put to rest rumors that drug use at the high school is a big problem, so he arranged a surprise lockdown and search of the building yesterday.

"Overall, it was a very large search that turned up a very small quantity of drugs," police Lt. James Hashem said. "We were very pleased with that."

Students and teachers were confined to their classrooms while 15 drug-sniffing dogs and their handlers roamed the corridors and searched 20 classrooms and hallway lockers.

The search came on the heels of 10 drug arrests in incidents in town last weekend. Six of the 10 arrested are Andover High School students.

Anderson said he and Police Chief Brian Pattullo made the decision together to conduct yesterday's search to combat the "innuendo, gossip and rumors that drug use at Andover High School is a problem."

"It was an effort to say to this community that it's not a problem within the high school," Anderson said. "Both of us have gotten a little frustrated with it."

Hashem said the dogs found a small, personal-use quantity of marijuana in one student locker, and the case was being handled administratively.

But when the dogs went through the parking lot, one of them hit on the car of a high school student, and police found five bags of marijuana inside, Hashem said.

Nicholas Sylvester, 17, of 294 S. Main St., was arrested and charged with possession of marijuana with intent to distribute and possession of marijuana with intent to distribute on school grounds.

Hashem said the drug sweep was in partnership with the high school administration, and it used police dogs from Andover, surrounding communities and from Essex, Suffolk and Middlesex County sheriffs departments.

Hashem said police and school officials were pleased that, given the magnitude of the search, very little marijuana was found inside the school.

"Clearly, if there is illegal drug activity, and obviously there is, it is not taking place within the school," Hashem said.

Hashem said the school used the lockdown procedure to keep students and teachers in the classrooms and to prevent them from walking in the hallways while the dogs were conducting the searches.

"We wanted to put to rest fears that these drug problems we are seeing in the streets at night and on weekends are also in the schools," Hashem said.

Anderson said the search was not specially the result of last weekend's arrests.

"Chief Pattullo and I have been talking about doing this for over a year, and we actually picked this date over a month ago."

Anderson said he was surprised that even one arrest was made after the search.

Anderson said police did not have enough evidence to arrest the male student found with drugs inside the school.

Anderson said 20 randomly selected classrooms were searched, along with student lockers and cars in the school parking lot.

"The students were treated with great dignity," Anderson said. "I'm sure there will be some parents questioning why it was done. We didn't target any individual students."

Andover High has more than 1,700 students and 150 teachers and faculty members.

Hashem said a similar but less extensive search was conducted last year, and no drugs were found then.