PHILADELPHIA (WPVI) -- Authorities say they found human remains in a Philadelphia park on Sunday night.

According to police, bones were found at Penn Treaty Park in the city's Fishtown neighborhood just before 5 p.m.

The medical examiner later determined that the remains were leg bones that had been washed up from the river, investigators say.

Officials said the bones appeared to be a femur and a tibia, or the upper and lower leg bones.

Authorities are unsure of the age and gender of the person the bones belonged to.

The medical examiner, however, believes the decedent has been dead for a long period of time.

Anyone with information on this incident is asked to contact the police.