The incident happened Thursday, after the school's black history program.
Spokesperson Pam Smith says four boys touched a girl in an improper manner when she went to get items from the band room. The issue launched an immediate investigation.
Little Rock Police are now involved.
Letters and recorded phone messages were sent to parents Friday.
Smith says parents weren't notified Thursday because the incident happened right before dismissal. She adds the district aims to be transparent, but has to gather all the facts first before alerting parents of any misconduct.