BAGHDAD, Dec. 22 -- An explosion tore through a crowded U.S. military mess tent in the northern Iraqi city of Mosul on Tuesday, killing at least 22 people and wounding about 70. U.S. military officials updated the casualty toll late today, saying that 14 of the dead were U.S. soldiers, and most of the casualties were Americans who had just sat down to lunch.
It was the deadliest attack on a U.S. military installation in the 21 months since the war in Iraq began.
The explosion, which came at noon, was at first believed to be caused by a mortar round or rocket that pierced the white canvas tent that serves as mess hall at Forward Operating Base Marez, near the Mosul airport. But U.S. officials said late today that it was likely a suicide bombing.
In an online assertion of responsibility for the attack, a radical Muslim group yesterday described "a suicide operation."
The press information center for U.S. forces in Baghdad announced in an e-mail late today that of the 22 people killed, 14 were U.S. military personnel, four were U.S. civilians, three were Iraqi Security Forces and one was an unidentified non-American. Sixty-nine people are now believed to have been wounded -- 44 of them U.S. military personnel. Twenty-nine people have been released from the hospital, the announcement said.
Two soldiers attached to the Richmond-based 276th Engineer Battalion, a Virginia National Guard unit, were among the dead, according to a Richmond Times-Dispatch reporter who was embedded with the troops.
President Bush, who was visiting families of wounded service members at Walter Reed Army Medical Center in Washington, said: "We send our heartfelt condolences to the loved ones who suffered today. We just want them to know that the mission is a vital mission for peace."
Halliburton Co., a Houston-based firm whose subsidiary Kellogg Brown & Root supplies food service and other support activities for U.S. troops in Mosul, said some of its employees and subcontractors were killed in the blast, Bloomberg News Service reported. Their nationalities were not reported.
"There is no road map for coping with events like this and we are doing everything we can to support our KBR personnel in Mosul," Halliburton said in a statement quoted by Bloomberg.
The attack realized the worst fear of U.S. commanders, who go to great lengths to make sure soldiers are not gathered in the large numbers that can lead to mass casualties. Dining facilities present the greatest challenge, especially at forward bases, where meals typically are served in a vulnerable structure like the cavernous tent at the crest of a hill at Marez.
The interior is larger than a football field, and several hundred soldiers were inside when the blast blew many off their chairs, according to Jeremy Redmon, the Richmond Times-Dispatch reporter embedded in Mosul.
Writing on the newspaper's Web site, Redmon described scenes of chaos -- a floor covered with bright red blood, lunch trays, overturned chairs -- followed within moments by determined efforts to aid the scores of wounded. Medics rushed in with canvas stretchers while soldiers used tables to carry out the badly injured.
The Web posting of the Army of Ansar al-Sunna, which asserted responsibility for the blast, referred triumphantly to the Black Hawk medevac helicopters that insurgents saw flying out of the base. The group, which has asserted responsibility for numerous suicide attacks and beheadings, is a successor to Ansar al-Islam, the al Qaeda-linked, largely Kurdish group that operated from a base in northern Iraq before the U.S.-led invasion.
"Scores of troops crammed into concrete bomb shelters outside," Redmon wrote. "Others wobbled around the tent and collapsed, dazed by the blast."