SNELLVILLE, Ga. -- A Gwinnett County high school principal is apologizing after several members of the school's marching band spelled out a racial slur during a recent performance, reports CBS Atlanta affiliate WGCL-TV.

The Associated Press said it happened during a half-time show.

Bo Ford, principal of Brookwood High School in Snellville sent a letter to parents detailing the incident.

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In the letter, Principal Ford explained that some of the instruments have covers that spell out the name of the school's mascot, "Broncos."

The covers aren't normally worn on the field but pictures posted to social media showed some of the band members spelling out a four-letter racial slur that starts with the letter "c."

Principal Ford called the term "hurtful, disrespectful and disappointing."

He also called it a "completely unacceptable, racial term" and said the school's halftime procedures now being reviewed, the AP reported.

He said the students involved would be disciplined.