BOSTON -- Students at Tewksbury Memorial High School were evacuated on Tuesday morning after a bomb threat was found at the school, police said.

Police said a threat was found on a bathroom wall, and the bomb squad, including a K-9 unit, was called in to search the school.

The handwritten threat said someone was going to "blow up the school," police said.

The students were moved to the nearby John F. Ryan Elementary School. The students returned to the high school after nothing was found during a search of the building.