() Police in southern Minnesota saw two drones flying around a nuclear plant Wednesday but were unable to identify the pilot.

Shortly after 6:30 p.m., local dispatch received a call about “four to five” drones flying around the Prairie Island Nuclear Plant in Welch, Minnesota, according to a news release from the Red Wing Police Department.

When officers arrived, they spotted two drones flying around the nuclear plant and Lock and Dam #3. The officers continued to monitor the drones until they left the area, the release said.

Police were unable to locate the drone pilot or pilots.

“There is no active threat to the public and the incident is not currently under active investigation by the Red Wing Police Department,” the release said.

Drones are prohibited from flying over nuclear power plants and other “sensitive facilities,” according to the Federal Aviation Administration.

Prairie Island is one of two nuclear power plants in Minnesota. It’s located along the Mississippi River near the Wisconsin border.