Iraq's largest oil refinery was shut down on Saturday after militants carried out a bomb attack and set it on fire, the governor of Salahuddin province said. The militants killed four people and planted bombs at production units for kerosene and benzene at the refinery in the town of Baiji, a former al Qaeda stronghold about 180 km (112 miles) north of Baghdad, Governor Ahmed al-Jubouri said. "There is a big fire in the refinery and the refinery has completely stopped," Jubouri told Reuters. Overall violence in Iraq has dropped sharply since the peak of sectarian conflict in 2006-07, but...