A sister ship of the cruise liner that ran aground in Italy last month was adrift Monday in the Indian Ocean with 636 passengers on board, including eight Americans, after a fire broke out in the engine room. No casualties or injuries were reported on the Costa Allegra, which is owned by Costa Cruises, the same Italian company that operates the Costa Concordia. A fire broke out in the electric generator room, but was promptly extinguished. The fire did not spread to other parts of the ship, but the engines were stopped. The cruise ship sent out a distress signal, summoning tugboats and naval ships to its location, about 200 miles southwest of the Republic of Seychelles in the Indian Ocean, in an area known to be frequented by pirates.