Detectives took 33-year-old Albert Anthony Morales into custody at his Diamond Bar home on Tuesday.
Investigators say Morales had been tutoring band students for the past 13 years in schools in Los Angeles and Orange counties.
Officials say Morales taught and volunteered as a percussion instructor at Diamond Ranch High School (2012-2013), Sunny Hills High School (2004-2009) and Diamond Bar High School (1998-2000).
Morales is being held on $350,000 bail.
Detectives are asking for the public's help in identifying any additional victims. If you have any information that can help investigators, you're urged to call the Los Angeles Sheriff's Department's Special Victims Bureau at (877) 710-5273.