Federal authorities are looking into reports that a man arrested with rifles, ammunition and drugs in his truck may have made threats against Barack Obama, officials said Monday.

FBI spokeswoman Kathy Wright confirmed the FBI was investigating the reports but declined to elaborate. The Joint Information Center – a command set up by Denver, state and federal authorities to field media inquiries during the Democratic convention – said it had no immediate comment.

Tharin Gartrell, 28, was arrested during a traffic stop early Sunday by police in the eastern Denver suburb of Aurora. In his truck, officers found two rifles, including one with a scope; a bulletproof vest; boxes of ammunition; walkie-talkies; and suspected narcotics, said Aurora police Detective Marcus Dudley.

Police alerted federal authorities, who soon arrested Nathan Johnson, 32, at a hotel in Denver, Dudley said. A third man, Shawn Robert Adolf, 33, was arrested at a suburban Glendale hotel, Dudley said.

Law enforcers in Denver are trying to find out whether the reported threats to Obama were valid. “It could also turn out that these were nothing but a bunch of knuckleheads, meth-heads,” the U.S. government official said.