The victim has been identified as 18-year-old Fabian Johnson of the 4800 block of Rorer Street.
He was found by the children on Saturday.
Police say Johnson had been dead for some time and had been shot multiple times in the head.
According to investigators, the shooting happened on a dirt road in Tacony Creek Park called Maple lane, which is near the intersection of Whitaker Ave. and Loudon St.
There is no word yet on a motive or suspects in this crime.