KARBALA, Iraq — American-led forces surrounded the headquarters of a militant Shiite leader near one of Islam's most revered shrines Saturday and set up roadblocks to prevent more of his supporters from entering the town center a day after three U.S. soldiers were killed in a brief but violent firefight with his bodyguards.

The battle here between U.S. and Iraqi police and the followers of Ayatollah Mahmood Hassani claimed the life of a U.S. military police battalion commander and left several Americans wounded. Two Iraqi police officers and a large but undetermined number of Hassani's armed followers also were killed.

Shortly after midday Saturday, a coalition military vehicle rigged with powerful loudspeakers pulled up on a main street a few hundreds yards from Hassani's office and began blaring out a demand that he and his followers lay down their arms.

"Attention! Attention! Attention! You are surrounded; it is useless to fight," the speaker declared in Arabic. "You are close to the holy shrines. You have to respect them and you have to respect the clerics. Stop fighting. No more bloodshed is necessary. There is no need for more victims."

In a tent at a Polish military headquarters a few miles from the scene, the head of coalition military forces in Iraq, U.S. Army Lt. Gen. Ricardo Sanchez, met with local commanders and at least two other Army generals for about an hour, apparently discussing how best to end the standoff. The American officers included the 1st Armored Division's assistant divisional commander, Brig. Gen. Curtiss Scaparrotti.

The senior officers' presence underscored the high stakes involved for the United States in ending the standoff without more fighting. Shiites make up a majority of Iraq's population and in general have been supportive of the U.S. occupation, in part because they suffered so during the rule of Saddam Hussein, who is a Sunni Muslim. Any serious erosion of Shiite support could seriously jeopardize America's effectiveness in Iraq.

None of the senior officers was prepared to comment on the operation.

"We can't talk about events that are still going on," explained Capt. Vojtek Majeran of the Polish army, which is deployed in the city.

As night fell Saturday, U.S. troops, supported by Humvee vehicles, kept the alleys and narrow streets near Hassani's main office closed off amid rumors that they might move against the armed fighters that remained inside at some point during the night. Five M-1 Abrams tanks blocked a larger approach road leading toward the headquarters, and U.S. Army Blackhawk helicopters circled overhead.