FBI agents and a local public corruption task force raided Palm Springs City Hall armed with search warrants on Tuesday, sending home employees and closing the offices for the day, an FBI spokeswoman said.
Spokeswoman Laura Eimiller said she could not disclose the nature of the searches, which were conducted with members of the so-called Inland Empire Public Corruption Task Force, because the case was under seal.
Eimiller said no suspects had been taken into custody in the desert resort community about 110 miles (177 km) east of Los Angeles and that no arrests were planned on Tuesday.
"We arrived at about 9 a.m. and expect to be out here for several hours, if not all day," she said.
The local Desert Sun newspaper reported that the raid came some three months after the state's Fair Political Practices Commission opened an investigation into links between Palm Springs Mayor Steve Pougnet and a real estate developer.
That investigation followed reports in the Desert Sun about the mayor's business relationships with that developer and an editorial saying he owed voters an explanation.
Pougnet responded in a post on his website in May that with the editorial the newspaper "threw their hat in with the handful of politically motivated detractors who have made accusations about my job as a consultant and my integrity as your mayor."
Pougnet, a 52-year-old Democrat who was first elected mayor of Palm Springs in 2007, announced in that same post that he would not seek reelection in 2015.
The mayor could not immediately be reached for comment by Reuters on Tuesday morning while the raid was under way.
Eimiller declined to say if the FBI raid was connected in any way to the mayor.