PHOENIX, Ariz. (NewsNation Now) — A Phoenix police officer is under criminal investigation for allegedly sending a credible threat to Mayor Kate Gallego.

Sgt. Mercedes Fortune, a public information officer for Phoenix Police, said the officer is now on administrative leave while the criminal investigation is handled by Tempe Police. Simultaneously, the Phoenix Police Department’s Professional Standards Bureau is conducting an internal investigation.

“The mayor’s office is aware of a credible threat made by a member of the Phoenix Police Department to harm the mayor. We are also aware an investigation is underway. Additional police protection has been provided to the mayor. We have no further comment at this time,” Mayor Gallego’s Office said in a statement.

A spokesperson for Mayor Gallego said they learned of the alleged threat last week, but declined to reveal when exactly.

Phoenix Police said this first came to their attention after it was reported to the Professional Standards Bureau.

The mayor’s spokesperson declined to elaborate on the nature of the threat, how it was sent, or if it was sent directly to the mayor.

The identity of the officer under investigation is still unknown.

Sgt. Fortune reaffirmed the department is taking steps to ensure the mayor’s safety. She said, “The Phoenix Police Department takes claims of misconduct by its officers seriously.”

In a statement Tuesday night, Tempe Police said, “According to the information from the Phoenix Police Department, the employee made a threatening comment against Phoenix Mayor, Kate Gallego. At this time, Tempe Police Department is still gathering details of this incident as this remains an ongoing investigation. No further information is available.”

The Arizona Department of Public Safety said they were not aware of the investigation when asked if they are involved.