Authorities say there have been at least four incidents since Feb. 19th.
"He's a sicko, These guys are dangerous, I mean they're truly predators and you got to get them off the street quick," Upper Darby Police Superintendent Michael Chitwood said.
First, in an alley near Derwyn Road and Highland Avenue where he approached four boys asking for their names and where they lived.
Then four days later at Forrest Avenue and School Lane, the man approached a 15-year-old friend of Danielle Millio, exposed himself and performed a lewd act in full view.
"She was really shooken up by it, she didn't know how to react. It didn't hit her until after it happen, what really actually happened to her. She felt awkward, didn't feel comfortable," Millio said.
Police say yesterday morning at Brookfield Road and Huey Avenue, the suspect, said to be driving a minivan, drove up to a 15-year-old girl who was walking to school.
"She noticed the van following her, she looks over and she sees the male masturbating, looks at her, she looks at him and takes off," Chitwood said.
Then this morning, in the Stonehurst section of Upper Darby, the man approaches a 14-year-old boy walking to school and asks him to get in his van. The boy refused and ran off.
School authorities have been making reverse 911 calls alerting parents about this man.
The person is described as a heavy set white male in his 50s with dark hair and salt and pepper facial hair. He is believed to be driving a dark blue or green minivan, possibly a Chevy Montana with grey interior.
Anyone who spots the man or his minivan is being asked to call 911.
