KNAPPA, Ore. (AP) -- Vandals swinging axes or baseball bats broke every window of a small northwest Oregon high school, and the district shut down classes for the day.

The Knappa district along the Columbia River in Clatsop County has only two schools-- the high school where vandals left shards of expensive double-pane class Monday morning and the adjacent elementary school.

Superintendent Rick Pass says he closed the elementary school, too, so the pupils would not be exposed to the profanity and obscene gestures in the graffiti the vandals left. It included a bomb threat.

Given good weather, Pass said, the schools may reopen Tuesday, even if the glass hasn't been replaced.

More than 100 windows were broken. Deputies say it's likely more than one vandal was at work.

Pass said even though it appeared no one had entered the school, the deputies conducted a bomb check and searched all the students' lockers, but found nothing.

Deputies were called about 3 a.m. when someone using the track heard glass breaking, Pass said.

Pass told the Daily Astorian he doubted a current student caused the damage, but Clatsop County Sheriff Tom Bergin was not so sure.

He noted that an 18-year-old Knappa High School student was arrested for a bomb threat at the school in November and called the vandalism "typical selfish behavior, probably by students."

He said there were four or five vandalism incidents last year, but the schools' rural location makes them hard to prevent.

"Our patrol guys are out there all the time, but they can see you coming," he told the paper.

The graffiti contained graphic comments about students that may be helpful in identifying the culprits, he said.

"We'll methodically pick it apart and someone will come forward," Bergin said.