VIDEO: After 3 Chiefs in 9 Days and Multiple Scandals, Oakland PD Now Run by City Admin

Oakland, CA's acting police chief Paul Figueroa stepped down Friday, becoming the third head of the Oakland Police Department to abruptly leave the top post in nine days, just as another bombshell dropped: A new internal investigation is under way, this time into racist text messages and emails shared among officers.

A visibly frustrated Mayor Libby Schaaf revealed the probe at a news conference Friday night that she began with a simple declaration: “I am here to run a police department, not a frat house.” With that, she disclosed that her city’s department, already engulfed in a sex scandal, was also being probed for racist communications that were “wholly inappropriate and not acceptable for anyone who wears the badge of the Oakland Police Department.”

The texts were sent by African American officers, Schaaf said. She would not give other details, including whether members of the police command staff were implicated, saying state law governing public release of police disciplinary matters prevented her from doing so.

Some of the officers being investigated were “engaging in hate speech,” and others were “tolerating it” by receiving offensive messages and not reporting them, Schaaf said. One text obtained by NBC news showed an image of a Ku Klux Klan member on a cereal box with the message, “Brad, I heard you got boxes of these in your cupboards.” Another text appeared to show the word, “N—.”

In a move in which the mayor indicated she had lost faith in police leaders to run the department, she disclosed that she would not appoint another interim or acting chief to the top post. Instead, the department will have no chief, and for the time being command staff will report to City Administrator Sabrina Landreth as Oakland conducts a national search for a new chief.