WARENSBURG, Mo. (AP) – A predominantly white Missouri school district is apologizing after a Donald Trump campaign sign was waved during player introductions for an all-minority Kansas City basketball team.

The Warrensburg school district apologized on its official Facebook page Tuesday, saying it would try to prevent similar incidents in the future.

Video posted online shows someone holding the sign in the Warrensburg High School student section and fans turning their backs as Center High School players took the court Monday.

Warrensburg Superintendent Scott Patrick tells The Kansas City Star the back-turning is a longstanding practice, but the campaign sign “took this from something that was unsportsmanlike to something that was insensitive, not necessary and inappropriate.”

Center’s spokeswoman says players were unaware of the sign during the game.

Warrensburg’s school district is 80 percent white. The Center district is 19 percent white.