SAADIYAH, Iraq — Iraqi police officers found explosives planted at a polling station Sunday morning here, the latest incident in a tense run-up to provincial elections in northeast Diyala province. The officers found two anti-tank mines with cell phone detonators at a school that will act as a polling station in Saadiyah, north of Baghdad in a part of Iraq disputed between Kurds and Arabs, U.S. military officials said. An Iraqi army explosives ordnance team defused and disposed of the explosives, officials said. Two men hired to guard the school were arrested for suspected complicity in the bombing plot, an...