Brutal Fury (1993)

Detective Molly Griffin is undercover at Lincoln High School to bust a drug ring. Her Fiance, Det Bill Thompson is also investigating some recent rapes, murders and discovers a secret vigilante group of girls called the Furies. The Furies recruit a strange, psychotic, cheerleader Misty into their group and her uncontrollable violent outbursts brother the members. Misty's dark past is slowly revealed as her violence against those "who don't belong" escalates as she murders the star football player who Det Thompson suspects of raping and murdering some other female students. When Misty decides to go after the drug dealers supplying her school, she goes to take them out and doesn't realize she might just be killing a cop.