Some members of a high school marching band in central Iowa say they were highlighting inequality when they walked off a football field during a performance of the national anthem.

The Des Moines Register reports 13 members of the Ames High School marching band linked arms Friday night and walked off the field during a performance of "The Star Spangled Banner."

The incident happened prior to a home football game against another high school. Some other band members reportedly did not play their instruments during the performance.

The newspaper reports some spectators in the stands cursed at the band members who left the field.

Band director Chris Ewan declined to comment after the incident. A message left by The Associated Press wasn't immediately returned Saturday.

Athletes, primarily national football players, have been protesting police brutality in recent weeks by either kneeling or linking arms during the national anthem. Others have stayed in their locker rooms.