Investigators determined he entered the school through an unlocked door in the student parking lot.
Nazarian is accused of approaching a 14-year-old girl, who was in a bathroom inside the school, and sexually assaulting her. Police said a "short struggle" took place between the two before he fled.
A Google Earth photo shows the entrance to Burbank High School in Burbank, California. (Google Earth)
Nazarian was stopped by school employees, who remained with him until police arrived.
During the investigation, police said a second 14-year-old girl and a 17-year-old girl reported they were both inappropriately touched by him.
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In a statement to Burbank police, Burbank Unified School District Superintendent Matt Hill said, "The Burbank Unified School District takes this incident very seriously and will cooperate fully with the police investigation. We are also conducting an internal investigation into this matter. Keeping our students safe is of the utmost importance."
Nazarian is being held on $1.2 million bond, and he is set to appear in court on Wednesday.
Burbank police said formal charges are pending review by the Los Angeles County District Attorney’s Office.
Anyone with additional information is asked to contact the Burbank Police Department Domestic and Family Crimes Unit at 818-238-3210.