(CBS/AP) CHICAGO - FBI agents have arrested a man they say planned to set off a car bomb outside a bar in downtown Chicago.

Federal prosecutors say 18-year-old Adel Daoud was arrested Friday night in an undercover operation in which agents pretending to be extremists provided him with a phony car bomb.

The U.S. District Attorney's Office in Chicago said in a news release Saturday the device was inert and the public was never at risk.

Daoud is a U.S. citizen from the Chicago suburb of Hillside.

He was charged with attempting to use a weapon of mass destruction and attempting to damage and destroy a building with an explosive.

Federal prosecutors say the FBI began monitoring him after he posted material online about violent jihad and the killing of Americans.

Daoud's father, Ahmed, spoke to CBS News by phone and said that Friday night was the last time he saw his son. He added that his son recently graduated high school. "I don't know, maybe you could tell me. I don't understand what he's done."

Daoud's sister, who did not want to be identified, told CBS News: "He would never do anything like that. He's only 18. He's at home all the time. This is out of thin air. I appreciate the information, but do not call us anymore."
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