WASHINGTON, June 22 (Xinhua) -- Seven people were arrested Thursday night in Miami, Florida, in an anti-terrorism operation carried out by agents of the U.S. Federal Bureau of Investigation (FBI) and state and local police, the Cable News Network (CNN) reported.

    No weapons or bomb-making materials had been found in the searches so far, and the Miami area was under no imminent threat, the report said, citing law enforcement sources.

    The seven arrests were made in connection with "suspected domestic terrorist activity," and that documents related to the investigation had been sealed, the report said.

    One of the arrests was made before Thursday, officials were quoted as saying.

    FBI Director Robert Mueller told the news channel that he could not get into details about the investigation as it was an ongoing operation.

    More details would be available when the operation was completed, probably Friday morning, he said.

    An Associated Press said the arrests were made in connection with the early stages of a plot to attack Chicago's Sears Tower and other buildings in the United States, and those arrested were mainly Americans with no apparent ties to al-Qaida or other foreign terrorist organizations.

    Attorney General Alberto Gonzales will hold a news conference Friday regarding the raids, and a simultaneous news conference is to be held in Miami. Enditem