CRYSTAL CITY, Texas (AP) — Officials say several people have been arrested in a public corruption investigation that's closed a city hall in a South Texas town.

FBI spokeswoman Michelle Lee says Crystal City's City Hall was closed for all business Thursday amid the investigation. She says unspecified law enforcement operations were being carried out in Crystal City and in San Antonio.

Law officers were seen Thursday morning removing boxes of documents from the City Hall in Crystal City, a town of about 7,100 located 100 miles southwest of San Antonio.

Lee declined to say who was arrested in the investigation also involving San Antonio police, Texas Rangers and U.S. Customs and Border Protection. Authorities planned to release more details later Thursday.

Several messages left at City Hall weren't immediately returned Thursday.