Assault on Hotel Kills 16 in Baghdad

No American service members were killed or wounded in the assault, which also included rocket fire, according to a U.S. military statement. An American soldier stationed at the site, which also includes the Sheraton Hotel, fired at the oncoming cement truck, helping to disable it, the statement said.

The other vehicle bomb in the attack detonated near an Interior Ministry office behind a mosque on Firdaus Square, where a large statue of former president Saddam Hussein was toppled at the close of the U.S. invasion of Iraq in 2003.

In leaflets distributed by masked gunmen in the western city of Ramadi, an insurgent unit affiliated with the group al Qaeda in Iraq asserted responsibility for the attacks, saying it had struck "the base of blasphemy, crusaders and infidels." The unit, the Lions of Braa Bin Malik, said the attack "killed the manager of the largest security company working in Iraq" as well as "a number of foreigners."

Among the tallest buildings in Baghdad's skyline, the Palestine and Sheraton hotels have been frequent targets of attacks, beginning on April 8, 2003, during the invasion, when an American tank shelled the Palestine, killing two journalists there. The buildings were repeatedly hit by rockets and mortar shells last year but had not been attacked in recent months.

Journalists in the hotel on Monday described a string of huge explosions that devastated the ground level and blew out windows several floors up. "The lobby of the hotel is completely trashed. I found pieces of the cement mixer 150 meters away from where it exploded," said one Western journalist staying at the Palestine, who said his company had asked him not to give his name for safety reasons. "Even by the standard of Baghdad car bombs, this was a large one."

Elsewhere Monday, the military announced that a Marine died Sunday in a firefight in Ramadi.

South of Baghdad, police found the bodies of 18 people who had been shot dead. Twelve of them, discovered in Musayyib, were laborers killed by gunmen driving a black BMW, according to police Capt. Muthanna Ahmed. Six others were found in Iskandariyah, about 30 miles south of the capital, he said.

Al Qaeda in Iraq called Monday for the killing of three prominent Sunni Arab sheiks in the insurgent stronghold of Anbar province, accusing them of working with the U.S. military there. A rift has emerged in recent months between some Iraqi Sunnis, who are believed to make up the bulk of the insurgency, and al Qaeda in Iraq, which is led by Jordanian-born Abu Musab Zarqawi and thought to be dominated by foreign fighters.

Also Monday, the commission tabulating the results of the referendum said that 96 percent of voters in Anbar province had rejected the document, a figure that makes Anbar the second Sunni-majority province to reject the constitution.

To block passage, opponents need to muster two-thirds majorities in three of Iraq's 18 provinces. Nineveh is the lone province with a sizable Sunni population whose results are not yet known. Early reports suggested that the constitution passed there.

Special correspondents Saad Sarhan in Najaf and Bassam Sebti in Baghdad contributed to this report.