Coalition forces have exchanged gunfire with Iraqi protesters in southern Iraq. At least 19 people are dead and more than 100 others were reported wounded in the shootout in Najaf.
Coalition officials say the shooting started when supporters of radical Shi'ite cleric Moqtada Sadr opened fire on Spanish troops trying to enter a coalition military garrison in the holy city.
Reuters (news agency) says four Spanish soldiers were among the dead.
In Baghdad, U.S. Administrator Paul Bremer condemned the violence. He said Iraqis have the right to freedom of expression, while urging dissenters to express their views responsibly.
The protesters were demonstrating against last week's closure of the militant al-Hawza newspaper that U.S. officials say was used by Moqtada Sadr to incite anti-American violence.
The crowd was also protesting Friday's reported detention of a senior Sadr aide by Spanish forces. Spanish military leaders deny detaining the aide.
Pro-Sadr demonstrations also erupted Sunday in Baghdad. Gunfire was reported, as hundreds of Sadr loyalists blocked the entrance to coalition headquarters in the capital. Details of the confrontation were not immediately clear.
Elsewhere, a car bomb apparently aimed at a U.S. military convoy exploded in the northern city of Kirkuk, wounding at least three people.
Earlier, U.S. military officials said two U.S. Marines were killed in fighting against Iraqi insurgents. One Marine died during fighting Saturday in Iraq's western Anbar province. The other died today (Sunday) from wounds suffered in a separate incident Saturday in Anbar.
The area west of the capital, Baghdad, is a hotbed of anti-American activity.
Information for this report is provided by AP, AFP and Reuters.