A serial exposer is on the loose after three separate incidents this week in Nassau County, including an attempted robbery.

The victim in the first case was a 17-year-old girl walking home from Valley Stream High School. Police say just after 4 p.m. Tuesday, a man driving a black sedan approached the girl on East Beverly Parkway and asked for directions. Police say she then noticed he was fondling himself.

About 40 minutes later, authorities say the same man approached a 56-year-old woman walking her dog on Brixton Road South in Garden City South and again exposed himself.

On Thursday, shortly after 4 p.m. on North Grove Street in Valley Stream, police say the man got the attention of a 47-year-old woman, exposed himself, pointed a handgun at her, and demanded money.

All three victims ran away and called 911.

According to Detective Lt. Richard LeBrun, the suspect is a black man, around 25 to 30 years of age and driving a black or dark-colored sedan.

“Quite possibly a Mercedes-Benz,” he says. "Always be cognizant of what's going on around you… If you see or hear anything suspicious, call 911 right away."

Authorities are urging anyone with information to call Crime Stoppers at 1-800-244-TIPS.