WATERLOO, Iowa (AP) -

Authorities say a knife has been taken from a third-grader after the boy menaced another boy at a Waterloo school.

Superintendent of schools Gary Norris says principal Stephanie Mohome told parents in a letter about Thursday morning's incident at Lincoln Elementary School.

Authorities say a boy saw another boy pull the knife and threaten a third boy. The witness told school workers, and the knife was confiscated. The knife reportedly had a 3-inch-long blade. No injuries have been reported.

Norris says the district will take disciplinary action, and law enforcement authorities are considering pursuing a juvenile case.