Police in Delaware and New Jersey say they've received multiple complaints about mysterious music from towns located along the Delaware River.
According to the News Journal, the source of the bass has not been identified, despite multiple complaints.
Delaware State Police Cpl. Michael Austin wrote in an email his department received calls about the music on Oct. 14, 23 and 28.
New Castle County police Officer Grigori Lopez Garcia says his department received similar complaints on Oct. 23, 26 and 27.
On the other side of the river, NJ Advance Media reports the New Jersey towns of Pennsville, Carneys Point and Penns Grove made dozens of calls about the music in October.
Delaware River and Bay Authority spokesman Jim Salmon says agency police aren't involved in the investigation.
AP wire services helped contribute to this report.