Both incidents happened on Naperville Park District property over the past week.
The first incident happened last Tuesday around 7:45 p.m. near Hillside Road and Washington Street, and the second incident happened Sunday around 7:30 p.m. near Gartner Road and Edgewater Drive. Neither victim was injured.
Investigators released images of the suspect, who they say is likely between 17 and 22 years old. He was riding an E-bike and wore dark clothing, a larger backpack, and Apple-style headphones.
Naperville Crime Stoppers are offering up to a $1,000 reward for information leading to the suspect's arrest.
Naperville police asked anyone with information to contact them at 630-548-2955 or NapervilleCrimeTips@naperville.il.us or Crime Stoppers at 630-420-6006 or www.napervillecrimestoppers.com. Callers to Crime Stoppers may remain anonymous.