Human Leg Bones Discovered in Philadelphia Park as Authorities Say Remains Washed Up from River

Two human leg bones were recently found at a Philadelphia park, although authorities are still trying to figure out who they belong to and what might have happened to them.

Around 5 p.m. local time on Sunday, Nov. 3, a passerby told police they saw two bones near the Delaware River at Penn Treaty Park, according to CBS affiliate KYW-TV and USA Today.

Police said the bones were "located in a grassy, rocky area along the park’s waterline."

The medical examiner later determined that the remains were leg bones and that they washed up from the river, according to KYW-TV and ABC affiliate WPVI-TV.

Although officials say they bones appear to belong to an adult, additional information remains unclear, KYW-TV reported.

Philadelphia Police Inspector D F Pace said there no clothing was found near the bones, and that authorities are not sure how they wound up in the river, or if a crime occurred.

Pace also told local NBC affiliate WCAU that the individual had seemingly been dead “for some time”

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

“At this point now it’s just a matter of conducting a forensic examination and trying to determine who these bones might belong to,” Pace explained.

The Philadelphia Police Department did not immediately respond to PEOPLE’s request for comment.

Penn Treaty Park is where Pennsylvania founder William Penn is believed to have signed a treaty of peace with the local Lenape tribe under an elm tree in 1683, according to VisitPhilly.com.

The park opened in the Fishtown neighborhood 1894, though the tree fell in 1810.