FALLUJAH, Iraq (AP) -- U.S. troops battled Iraqi guerrillas today on the edges of Fallujah, which

FALLUJAH, Iraq (AP) -- U.S. troops battled Iraqi guerrillas today on the edges of Fallujah, which hundreds of Marines and Iraqi troops have surrounded in a major operation to pacify one of Iraq's most violent cities. The military reported four Marines killed in the area.
The Americans were killed by hostile fire Monday, bringing to five the number of Marines killed that day.
The military did not give details on the deaths, saying only that they took place in Anbar province, where Fallujah is located.
City sealed
U.S. and Iraqi troops have sealed off the city for more than 24 hours, blocking roads and digging trenches in preparation to move in to root out insurgents after the slaying and brutal mutilation last week of four American civilians.
Scenes of Iraqis dragging the four bodies through the streets and hanging two of the charred corpses from a bridge Wednesday raised revulsion in the United States and showed the depth of anti-U.S. sentiment in the city.
Radical cleric
Meanwhile, a radical Shiite cleric being sought by U.S. forces announced today he had left the mosque in the city of Kufa, south of Baghdad, where he has been holed up for the past two days, surrounded by armed militiamen.
Muqtada al-Sadr said in a statement released by his office that the "sanctity of a glorious and esteemed mosque would be violated by scum and evil people." The Americans "will have no qualms to embark on such actions."
The statement did not say where al-Sadr had gone.
U.S. administrators declared al-Sadr an "outlaw" Monday and announced a warrant for his arrest, suggesting they would move to arrest him soon.
The confrontation with al-Sadr -- whose militia waged fierce battles with coalition troops Sunday -- and the offensive against Fallujah appeared to be a tougher approach by U.S. forces ahead of a planned June 30 handover of power to an Iraqi government.
In Fallujah, explosions and gunfire were heard from the city through the night Monday and into this morning, apparently U.S. troops shelling targets and clashing with guerrillas as Marines probed the outskirts with reconnaissance patrols.
But the bulk of the force remained on Fallujah's edges today, and there was no word whether troops had carried out raids against what officials have said is a list of suspected insurgents being targeted.
A force of Marines pushed into an industrial zone in the eastern part of the city, clashing with guerrillas. Gunmen carrying automatic weapons were seen in the streets. The military reported six Iraqis killed in fighting Monday, saying they were all guerrillas, though residents said five of them were killed when helicopters hit a residential area.
Violence in Ramadi
In the nearby city of Ramadi, another hotbed of guerrilla activity 24 miles west of Fallujah, U.S. troops and insurgents clashed on a downtown street. One Iraqi was killed and three wounded, doctors said.
The offensive against Fallujah, 30 miles west of Baghdad, comes as the United States is taking a tougher approach against al-Sadr, who has long spoken out against the U.S. occupation and has built up his own militia, the Al-Mahdi Army -- though he has not called for anti-U.S. violence in the past.
Al-Sadr launched a wave of protests over the arrest of a top aide last week, sparking gunbattles Sunday between his militiamen and coalition troops in Baghdad and near Najaf that killed at least 52 Iraqis and nine coalition troops, including eight Americans.
Since that fighting, al-Sadr had been holed up in the main mosque in Kufa, south of Baghdad, vowing to resist any move to detain him. Dozens of his militiamen were around the mosque today, searching worshippers who entered through its tall outer walls to pray.
The showdown with al-Sadr threatens to heighten tensions between the U.S. occupation and Iraq's Shiite majority, who have largely avoided anti-U.S. violence -- though al-Sadr's popularity among Shiites is limited. U.S. officials appear to be counting on Shiites to shun al-Sadr, seen by many in his community as too young and fiery to lead.
In Najaf -- Shiism's holiest city, near Kufa -- fresh graffiti on walls praised al-Sadr, reading, "Yes to armed resistance, yes to the al-Sadr revolution" and "No, no to the Americans."
Al-Sadr's militia has appeared to control Kufa since Sunday, holding its police station and roaming the streets. Sheik Abu Mahdi al-Rubaie, a 35-year-old al-Sadr follower at the Kufa mosque, warned that any U.S. move against al-Sadr would be "a very dangerous thing."
"They will pay a heavy price. We will not allow them to enter Kufa. ... We are ready to lay down our lives" for al-Sadr, he said.