Macomb High School was on lock down as of 9:30 a.m. Thursday, according to school officials.
The K-9 unit is in the building, Jean Sawczyn, a member of the school's office staff said. All of the students are safe in the classrooms.
Sawczyn said that she wasn't allowed to say why the students were in the classroom or the nature of the threat to students that led to the lock down.
A statement released by the school district later Thursday said, "In an effort to keep our students safe, the Macomb JSHS conducted a lock down this morning. During that time, canine units from area law enforcement swept our building and parking lots for contraband. No arrests were made."