FALLUJAH, Iraq - Insurgents attacked a freight train with an improvised bomb Thursday, setting four containers on fire and setting off a spree of looting by residents, witnesses said. The attack occurred on a rail line four miles west of Fallujah against a train that carries freight, mostly for the U.S. military, from this city to Haditha, about 135 kilometers to the northwest. The engineer escaped injury and fled the scene, witnesses said. As soon as the flames subsided, local residents swarmed over the wreckage, carrying off computers, tents, bottled water and anything else they could carry away.