At least six workers were killed in a fire at a factory on the outskirts of India\'s southern city of Bangalore on Monday, a news report said. The fire engulfed an upholstery manufacturing unit in the early hours when the workers were asleep, the online edition of the Hindu newspaper reported. The workers were believed to have died due to suffocation as the shutters of the unit were closed from inside, fire officials said. The cause of the fire was unknown and it took fire engines some four hours to bring the blaze under control, according to a report of DPA.