Five containers of used syringes and blood vials were found Saturday by a group of friends out on the river in a boat.
The Pawnee County Sheriff's Office said investigators were trying to trace the waste — some of which was labeled with patient names — back to their source, which officials believe may be a private company hired to dispose of the biohazards safely, NBC News reported.
Sheriff Mike Walters warned residents to be on the lookout for hazards before swimming in the river.