dubai bahrain say wednesday bomb attack police bus kill officer wound nine last month carry militant cell train arch-foe iran authorities quash shi ite muslim-led arab spring protest sunni-ruled island 2011 militants launch deadly bomb shoot attack security force bahrain blame tehran shi ite theocracy iran deny role bahrain unrest immediate iranian reaction wednesday bahraini interior ministry statement add authorities arrest one member cell others fugitives iran terrorist cell receive extensive train iranian revolutionary guard camp use manufacture explosives firearms well material logistical support ministry say bahrain say early week explosion main oil pipeline friday cause terrorist sabotage link unprecedented attack iran key western ally host u.s. fifth fleet gulf arab monarchy bahrain years grapple protest sporadic violence come shi ite majority bahrain say deadly bus attack engineer iran