In a statement on Sunday, the FBI warned that there could be copycat attacks in the wake of this weekend's mass shootings in Dayton, Ohio, and El Paso, Texas. Already, a man in Florida has been arrested on suspicion of threatening to "shoot up" a Walmart in Gibsonton, Florida. Wayne Lee Padgett told authorities that "he was intrigued with the shootings over the last couple of days." Visit INSIDER's homepage for more stories.