A U.S. helicopter has been shot down on the western outskirts of Baghdad, killing both crew members. The latest American military loss comes amid U.S. efforts to consolidate a cease-fire with Iraqi combatants in the strife-ridden city of Fallujah.

U.S. Brigadier General Mark Kimmitt said at a news conference in Baghdad, neither crew member of the Apache attack helicopter survived Sunday's shootdown. "We have a quick reaction force on site conducting the recovery of the equipment and the personnel," he said.

Reports say American tanks and other heavy equipment have moved into the area, where masked gunmen have attacked fuel convoys and other targets in recent days.

Meanwhile, a spokesman for the U.S.-led coalition in Iraq, Dan Senor, said it is hoped that a tenuous cease-fire in Fallujah will prevent further bloodshed in the city, regarded as a hotbed of anti-American sentiment.

"We are trying to suspend hostilities, so that the Iraqi Governing Council delegation can get in and out of Fallujah easily to have discussions with Fallujan leaders," he said. "Once we get comfortable with that phase, we can talk about the nature of those discussions that could perhaps lead to something more permanent."

But Mr. Senor stressed that no one should question U.S. resolve to quell uprisings and insurgencies in Iraq. "When the mob violence that has run rampant in certain parts of the country is left unchecked, it is not going to go away, if we choose to ignore it," he said. "And that, certainly, would pose much larger problems down the road for Iraq's path to democracy."

Speaking on the U.S. television program Fox News Sunday, U.S. Administrator for Iraq Paul Bremer said the recent surge in anti-coalition violence in Iraq must be viewed through a historical perspective.

"I think what is going on here is effectively to purge some of the poison that built up in the body politic of Iraq for 25 years of Saddam's tyranny," he said. "There is a lot of poison still in the society, and it has got to come out. And, frankly, it is better that it comes out now, rather than later. We always knew there were going to be rough days during this occupation, and we certainly have had a rough week [in Iraq]," he said.

Mr. Bremer said the violent actions of several thousand Iraqis opposed to change must not be allowed to frustrate the hopes of millions of others who want a democratic system. He said that the planned June 30 transfer of power remains on target, and that he believes that a functioning Iraqi administration will be in place by that date.

President Bush echoed that message, speaking with reporters in Fort Hood, Texas, after meeting with family members of U.S. servicemen in Iraq.

"This violence we have seen is a few people trying to stop the progress toward democracy," he said. "Fallujah, south of Baghdad - these incidents are basically thrust upon the innocent Iraqi people by violent gangs. And our troops are taking care of business."

Mr. Bush said he is in regular contact with U.S. military commanders in Iraq, and would consider any request, if one were made, to send additional troops in support of coalition efforts.