The FBI began a raid early Thursday morning at the San Antonio law offices of state Sen. Carlos Uresti, The San Antonio Express-News first reported.
FBI agents have been seen at the scene removing boxes from the offices approximately every 30 minutes.
"Law enforcement agents with (the) IRS and FBI are lawfully present conducting a law enforcement operation," FBI spokesperson Michelle Lee says in a written statement. "No further details can be released at this time."
No arrests have been made today, she added.