What appear to be "multiple” human remains were found partially submerged in a river in the small Oklahoma city of Okmulgee Friday, nearly a week after the disappearance of four adult friends, authorities said Friday.Prentice said he notified the families of the missing men, who were last seen Sunday night leaving a home by bicycle, even though the remains haven’t been identified.Friday's discovery occurred shortly before 2 p.m., when a passerby notified authorities of "suspicious" items in a shallow river southwest of the town of roughly 11,300, Prentice said.Investigators were documenting the scene through aerial video and photographs before they begin recovering the remains, he said.Although witnesses have reported seeing the men as far as away as Monroe, Louisiana, Prentice said the only thing confirmed about their movements after they left the home Sunday was based on GPS data from cell phones that two of the men are believed to have had with them."