(Adds quote, background) BAGHDAD, Jan 28 (Reuters) - Two U.S. soldiers were killed when their helicopter crashed north of the Shi'ite holy city of Najaf on Sunday, the U.S. military said. A Reuters reporter saw a U.S. helicopter come down after a burst of machinegun fire and he saw a trail of smoke from the helicopter before it came down. Iraqi police said it had crashed during a battle with gunmen north of Najaf in which 250 gunmen were killed. A U.S. statement said the helicopter "went down" but did not say whether it was shot down. "While conducting operations to assist Iraqi Security Forces that were attacked earlier today, a Multi-National Division - Baghdad helicopter went down at approximately 1:30 p.m. (1030 GMT) north of An Najaf," a U.S. statement said. "Two soldiers were killed when the helicopter went down. Their remains have been recovered," it said. U.S. and Iraqi forces killed 250 gunmen from a Muslim cult in Sunday's battle involving U.S. tanks and helicopters near Najaf, Iraqi police, army and political sources said. The day-long battle was continuing after nightfall, Colonel Ali Nomas told Reuters. A Reuters reporter on the scene saw several American tanks and other armoured vehicles arriving at the site of the battle, 160 km (100 miles) south of Baghdad. The fighting in Najaf, 160 km (100 miles) south of Baghdad, began as hundreds of thousands of pilgrims converged on the other main Shi'ite holy city of Kerbala, 70 km (40 miles) to the north, for the climax of the annual Shi'ite rite of Ashura.
