The FBI searched the office of California state Sen. Ron Calderon on Tuesday but would not disclose the reason for the investigation.
Laura Eimiller, the spokeswoman for the FBI office in Los Angeles, said the warrants were served about 3 p.m. and that agents remained inside the state Capitol in the evening.
She would not disclose the target of the search warrants, but Senate Chief Sergeant-at-Arms Tony Beard told The Associated Press it was Calderon, a Democrat from the Los Angeles County city of Montebello.
"It's a federal search warrant served on Sen. Calderon's office. It's a sealed search warrant. I don't know what it relates to," Beard said.
He said Calderon was not present during the search and did not know if the agents had removed any material.
Neither Calderon nor his spokesman, Rocky Rushing, immediately returned telephone messages left on their cellphones.
Eimiller said two warrants had been issued and were under seal in U.S. District Court but did not know if that was in Los Angeles or Sacramento.
Beard told reporters who gathered outside Calderon's office Tuesday night that the office of the legislative Latino caucus also had been searched.