Human error at a Duluth-area sheriff's office sounded an actual emergency siren on Wednesday, rather than the emergency test siren that cities and counties sound at 1 p.m. on the first Wednesday of the month.

Dewey Johnson, emergency support services administrator for the St. Louis County Sheriff's Office, explained: "During the test, one of our operators inadvertently pressed the warning button rather than the test button. This caused the wrong alert tone to sound.

"A lot of people likely aren't aware there's a difference between the test tone and the tone for a real emergency, but for those who do know, this may have caused concern, and for that we apologize."

The sirens sounded primarily in Duluth and nearby Proctor, the Sheriff's Office said in a statement.