A threatening email was sent to the Chicago Police Department’s civilian oversight agency Friday morning.

CPD spokesman Anthony Guglielmi said “an emailed workplace threat” was sent to a workplace in the 1600 block of West Chicago Avenue in West Town.

“There is no one injured or known offender identified,” Guglielmi tweeted, adding that a “visible police presence” would be in the area as authorities investigated.

The Civilian Office of Police Accountability is located on that block. Ephraim Eaddy, a spokesman for COPA, confirmed that the threat was sent to the oversight agency.

“Today the Civilian Office of Police Accountability (COPA) was informed by local law enforcement of the Chicago Police Department of an anonymous tip and potential work place threat,” Eaddy said in a statement. “As an agency, we take all matters regarding the safety of our staff serious and are cooperating with law enforcement officials as they continue their investigation.”

It’s unclear who sent the threat or what the message’s contents were.