Jacksonville International Airport in Florida was closed for six hours after a man going through security told a checker that he had a bomb hidden inside his camouflage backpack, authorities said Wednesday. The man, Zeljko Causevic, was charged with having a hoax bomb. He told authorities that the device — a luggage scale with two batteries and a microchip, plus a remote “detonator” — was “supposed to be a bomb, but it’s not.”A second man was stopped in an airport garage for acting suspiciously and was charged with resisting arrest, but he did not appear to be connected to Causevic,...