Federal agents arrested 22-year-old Derrick Shareef, of Rockford, Illinois.
They say they made the bust after Shareef met with an undercover agent in a parking lot, and that he was there to try to trade a set of stereo speakers for four hand grenades and a handgun.
Federal officials said Shareef planned to set off four hand grenades in garbage cans at the CherryVale shopping mall in Rockford, about 90 miles northwest of Chicago.