Police say the man was spotted touching himself while children played nearby in Bay Ridge.
It happened Monday afternoon.
A 51-year-old man who spotted the inappropriate act confronted the man, and that's when police say the assailant punched the man and ran away.
The witness was not injured.
Anyone with information in regard to the identity of this male is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
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