Updated

Seven people were arrested on terrorism conspiracy charges Thursday in connection with the early stages of a plot to attack Chicago's Sears Tower and other buildings in the United States, a federal law enforcement official said.

Officials told FOXNews the seven men were in the very early stages of planning an attack for what the planners thought was Al Qaeda, but the people they were working with were actually Department of Justice officials.

The target was supposedly the Sears Tower in Chicago, but officials said the suspects were also considering attacking FBI facilities and government buildings in Miami.

Officials told FOXNews that the suspects were plotting to wage jihad in conjunction with Al Qaeda and were having elaborate discussions, and that the suspects believed if they knocked down the Sears Tower, that they could effectively cripple the U.S. government.

The officials stressed that there was no imminent danger, telling FOXNews "we were with them the whole time."

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Those arrested include five American citizens, one illegal alien from Haiti, and one resident alien. All are expected to be arraigned in U.S. District Court in Miami tomorrow morning.

A federal law enforcement official told The Associated Press the alleged plotters were mainly Americans with no apparent ties to Al Qaeda or other foreign terrorist organizations. He spoke on condition of anonymity so as not to pre-empt news conferences planned for Friday in Washington and Miami.

U.S. Attorney R. Alexander Acosta said in a statement that more details about the ongoing operation would be released Friday. Local media reported that agents were raiding a warehouse in Miami's Liberty City section.

"There is no imminent threat to Miami or any other area because of these operations," said Richard Kolko, spokesman for FBI headquarters in Washington. He declined further comment.

Attorney General Alberto Gonzales was scheduled to hold a news conference on Friday to discuss the raid. A simultaneous news conference was to be held in Miami.

Cedric Thomas, an owner of Thomas Produce Market, told The Miami Herald the area around his store was teeming with federal agents.

"There is a ton of guys in uniforms moving around, blocking the streets," Thomas said.

Several terrorism investigations have had south Florida links. Several of the Sept. 11 hijackers lived and trained in the area, including ringleader Mohamed Atta, and several plots by Cuban-Americans against Fidel Castro's government have been based in Miami.

Jose Padilla, a former resident once accused of plotting to detonate a radioactive bomb in the U.S., is charged in Miami with being part of a North American terror cell.

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The Associated Press contributed to this report.