CHICAGO, Ill. — FBI agents say they have thwarted a terrorist plot to use a big rig to blow up the U.S.’s tallest building, the Sears Tower in Chicago.

Based on evidence seized from several men arrested across the Midwest, federal investigators believe they successfully disrupted a terrorist cell planning a possible truck bomb attack on the 110-story skyscraper.

Five individuals taken into custody: three in Detroit, one in Iowa and one in Chicago. At least four of the five men had fraudulently obtained hazmat licences. Among their possessions were drawings and information on computer disks relating to the 110-story skyscraper, according to law enforcement officials.

As of Oct. 1, no charges had been laid in connection with the incident and it was not know when the possible attack on the Sears Tower may have been slated for.

“We believe that there is the likelihood of additional terrorist activity and it is our job to do whatever we can to interrupt it, to disrupt it,” says U.S. Attorney General John Ashcroft. He adds federal authorities have so far arrested or detained more than 500 people in connection with its terrorism investigation.

Investigators in the U.S. and abroad believe Osama bin Laden is the one fueling the increased terrorist activity and they suggest he has hundreds of dedicated followers around the world ready and willing to violently resist efforts to destroy his terrorist network, al Qaeda.