DOVER, N.H. (AP) — A New Hampshire school superintendent is decrying a racially insensitive video of two high school students singing, "KKK, KKK, Let's kill all the blacks," to the tune of "Jingle Bells."

Fosters Daily Democrat reports a cellphone video surfaced over the weekend of the students singing the song in class at Dover High School.

Superintendent William Harbron said in a letter to the school community Monday the incident was part of an assignment dealing with the Reconstruction period in American history, but said, "the impact was harmful."

Harbron said the 11th-graders had to select a history event and create a jingle for it. Two students selected the Ku Klux Klan.

A decision on whether to discipline the students or teacher hasn't been decided yet.